Umm… the long and short of it is… you don’t.
I mean, I ride all year round (MA) but unfortunately it gets to the point where asking to W/T/C on snow is dangerous and I am relegated to walk-only from the months December-Feb/March, really. I generally will trail-ride those months and stay out of the ring. My guys look at about 3-5 rides a week in the winter and honestly probably 95% of it is done at the walk. I wish I had an indoor because those are the best months to really work on our dressage… unfortunately it isn’t the way the real world works. I think my guys do just fine though and I never come out of the winter feeling like I lost any big progress we made right before winter hit.
If the weather cooperates I will trailer/truck in to a local indoor but sometimes it isn’t worth the extra +1hr of time to do, especially as we get closer to spring and some of my guy’s core fitness is lost. I find they don’t lose too much condition that a few good weeks of interval training won’t put back on come spring.
The more you ride on the ring the more the snow underfoot will compact and get slippery/icy… So I’ve found the best way to do it is to ride only on one half of the ring for a few weeks, and then move to the other half once the footing starts to compact too much… Taking care not to cross your tracks too much, and hacking out of the ring every other day helps to keep the snow in the ring fluffy and not slick. Light powdery snow is the most slippery IME, you want the heavy snow that fully blankets the grass underneath - but then there is the working through snow – if it’s 3-6" that’s one thing but if you’re doing W/T/C through a foot of snow every day it can get hard on the horse.
My guy starts to tell me when he isn’t comfortable trotting in the snow anymore. That usually happens mid January when we get multiple snowstorms that layer new snow over old and flatten the old snow and make it slippery. Some people say they do lateral work when they can’t trot but honestly, if they can’t trot I cannot imagine how asking the horse to do lateral work is much better. My rule is if he slips a little behind once, we’re done trotting/cantering for the day. I had a full-out wipeout a few years ago in decent snow and I am a CAUTIOUS snow-rider, and if you go through a thawing/freezing phase you have to be careful because it can look fine & dandy up top but a horse’s hoof sinks deeper than yours - it’s not the snow you need to worry about, it’s the grass underneath.
As far as the dark? And staying motivated? I ride right away, the second I get home (6PM) yeah, it’s pitch black. I don’t have lights (yet) so have been using my car’s light[s] the last few years… turn my car to face the ring and put the lights on. Not great for the battery so I don’t do it often. If there is any moon out it usually is bright enough because it reflects off the snow, so more often than not I go without light especially if I am just walking. Moonlit nights riding through brisk snow can be quite fun!
I also have strapped a high-powered flashlight on my helmet for the hacks in the woods.
Staying warm? I layer and look like the Michelen Man… seriously. My go-to last year was a warm thick fleece PJ bottoms with a water resistant outer shell pant, with 10-BELOW SSG gloves, multiple sweaters and a Carhart Jacket. Socks and boots… I did thin socks w/ fleece socks over in Dublin boots and stayed quite toasty even in the negatives.
Get thee or make thee a nice warm quartersheet… On days I Do Not Want To Ride Today I think of snuggling up in the QS and that will keep me going.
Good luck. It’s tough. Winter in the NE without an indoor sucks and it’s one of the very few things in the world I can honestly say I hate.
I had a very narrow indoor that allowed us to do jump bounces and a bit of dressage, but we weren’t much better off!
No trails without hauling. I feel like some of the hills on the trails are pretty steep for winter riding (like you slide down) and could be a bit sketchy when the ground is frozen.