I know this has been discussed previously, but nothing too recent. Frankly, I’m frustrated. When I find coats, shadbellies, and breeches in plus sizes, I always check the size chart before ordering. Why do they assume (sorry, way TMI I’m sure) that if your bust is 42, your waist has to be 32? Seriously? There is not a 10 inch difference there for heaven’s sake! I was coaching at a rated show just last weekend, and I saw plenty of larger riders, beautifully turned out. Larger than me in many cases. So where do I find these clothes? All the brands I’ve found stop at XL or size 16 which turns out is still too small (not in regular clothes, it’s too big!) or are sold out. It’s disheartening. And please, don’t harass me about it. I’m post-menopausal and have a sedentary job. For reference, I’ve looked at SmartPak, Dover Saddlery, Dressage Extensions, and some site I don’t remember that came up when I did a google search.
I bet if you went up to a rider you admired when they were hot walking their horse or having a Margarita in the shade and said “I loved your jacket, you looked so well put together out there. I was wondering if you could tell me the brand?” they would be very happy to talk clothes!!!
It is really frustrating isn’t it?
I think they may get them custom made. I never rode well enough to need a shadbelly but I assumed that is what I would have to do.
Even the plus size riders clothes seem to fit smaller or have weird shapes like you mentioned.
Right now this is a problem with lots of things, even in the itty bitty sizes (which I do not wear either).
That whole supply chain, covid thing.
Many will feel and share your pain. The excitement of finding an equestrian garment that fits 2XL, then realizing that means size 14-16.
I second asking people you see, who doesn’t like to be complimented on their turnout.
Ugh. So right. I didn’t take that into account. I’m still dying to find caffeine free Diet Dr. Pepper which has been unavailable for over a year! 
YES! Me too! Darn them. I love that stuff!
What are you looking for specifically? Breeches? Jackets? Tails? Romfh goes up to size 40 in breeches and is expanding their jacket sizing. Maya Delorez breeches are really cute and stylish, nice enough for show and come in plus sizes. Kerrits makes a very flattering, stretchy, basic show jacket that goes at least to 1x and possibly higher.
I wear a 16/18 and was able to get a shoe coat from Kerrits - the Competitor stretch. I think I got a size 1x which their guide says is a 20-22. I usually need to err larger in coats due to my shoulders and arms. It comes in navy and black and I really like that it has the hidden zipper with buttons. And real pockets!
For breeches I wear the Buckwild curvy which go up to a 40. I’m like a 36. They are basically out of stock now, I emailed in early May and they said they’d be getting restocked in June but nothing yet.
All of the above! I found a NWT Pikeur shadbelly and promptly bought it. I need breeches and a short coat. (Was hoping to have my existing one let out, but alas there wasn’t enough fabric to make it work.)
I wear an 18 and have a SmartPak Piper soft shell jacket and the Kerrits Competitor one Zevida mentioned.
Kerrits short jacket - hidden zipper beneath the buttons so no boob gap, super stretchy, lightweight comfy material, and you can throw it in the washer and dryer: https://kerrits.com/products/stretch-competitor-koat-three-button
Romfh short jacket: https://www.romfh.com/product/romfh-bling-show-coat/
Romfh breeches: https://www.romfh.com/product/romfh-sarafina-bling-full-grip-breeches/
Buckwild breeches - as someone mentioned above their Curvy Mare plus size line is low on stock, but even their Signature series are comfortable. The XL fits like a 38, and they are budget-friendly: https://www.buckwildbreeches.com/products/signature-mid-waist-breech-white
Maya Delorez breeches: https://mayadelorez.com/product/iza-performance-breeches/
A lot of people have also recommended the Ovation Celebrity Slim Secret breeches to me, but I’ve never tried them.
Always look at the size guide when buying on the internet, and know your measurements!
Fuller Filly Sticky Vicky breeches are nowavailable here: https://www.plusinboots.net/boots-by-fuller-fillies/sticky-vicki-breeches-by-fuller-fillies.Yes they are in the UK, but shipping is quick, even during Covid.
They also have off the rack plus sized boots - I haven’t tried those, I go custom for boots, my custom Dehners last for more than ten years- my current scruffy working boots are coming up on 19 years old - Dehners in Dragoon leather: https://dehner.com/guides-info/leather-guide/
Celeris has a buy one get one half off deal going on custom boots, I got some for fun bling boots: https://celerisuk.com/pages/store. In my experience, larger ladies should avoid wasting their money on custom boots from LMboots or Vogel, neither company has the foggiest clue how to size a boot up.
RJ Classics makes very polished looking plus sized jackets: https://rjclassics.com/?s=plus&post_type=product&title=1&excerpt=1&content=1&categories=1&attributes=1&tags=1&sku=1&orderby=date-DESC&ixwps=1
Kerrits now makes mesh jackets in 1X and 2X for covering your fluff without making you faint when it is hot. They sold out of navy in a minute this Spring. I got the last navy one from Dover… Hopefully they will make a 4 button for next season. https://kerrits.com/products/affinity-aero-show-coat
Back to breeches, I find the curvy mare breeches from Buckwild to be fun for Summer wear, but not very protective of your skin for more than an hour in the saddle. Smartpak’s Winter breeches are great - they need to ditch the wine tasting color and do a hunter green for this next season… I have all the other colors. And someone needs to bang Smartpak’s head against the wall until they start making their plus sized Pipers with a realistic crotch depth. https://www.smartpakequine.com/pt/piper-winter-softshell-breeches-by-smartpak--full-seat-14846
And underneath it all, this bra to prevent self inflicted black eyes during sitting trot: https://www.wacoal-america.com/bras/sport-contour-underwire-bra-wacoal-853302
These are my favorites. They are very flattering over the lower tummy without being uncomfortably restrictive. The waist / hip ratio suits me well. Body shapes differ so general YMMV
I found Huntington Equestrian and ordered 2 pairs of white full seat breeches that fit great! I also got a short coat from Dublin that is actually a little big and will need to be taken in. I have my eye on a Pikeur shadbelly that I am saving up for. So all’s well that end’s well. But I sure appreciate all the suggestions! I should never have to run into this issue again. 
Can you add a diamond gusset to the breeches? Would that help? Also adding a panel to the coat if you can find a fabric that matches well-enough or maybe add it then overdye it. A good tailor/seamstress can work wonders, if one can be found.
Everyone looks better after a tailor has worked their magic.
Agree about the tailor. The coat really is too big. But not sure why you are asking about adding a gusset to the breeches. They fit perfectly. I already rode in them at a schooling show.
To minimize chafing in the most delicate area if the seams meet there. I have also added some padding there in the past. Just a bit because I have found cyclist shorts a bit too padded and it felt like a diaper.
I like the Ovation Slim Secret breeches as well, but have found that no manufacturers size up the calves to match larger waist sizes…the waist and hips will fit fine, but the calves are 2-4" too small (and I end up cutting off the bottoms just to get them up my legs)! And don’t get me started on “wide” boots that are 15" around.
Ariat Tri-Factors have a very, very stretchy lower calf with no banding around the ankle so they accommodate pretty much any width calf. They go up to a generous 36L.
