Cold averse NewEnglander here. I admit I’ve cut back on my winter riding, but before I had access to an indoor I would ride three horses on the beach every day that the tide timing was appropriate. (Can only ride +/- 2 hours of low tide). It was great for practicing figures as I could really see the tracks. And even now there are winter rides on the beach.
I would wear fleece tight-style breeches with a old pair of corduroy breeches on top because I hated that the fleece would grab every bit of hay or shavings in the barn and wasn’t windproof at all. (I should have worn my full chaps!) Top would always start with a cotton turtleneck then fleece 1/2 zip, fleece vest if really cold, but always one of those quilted Barbour style riding jackets with an LL Bean or Eddie Bauer rain jacket over top of equal length. My favorite quilted jacket was the Husky Stowmarket, in case you can find one. I still ride in one that’s about 30 years old. Good length and cut for riding, And an ever so important knitted cuff. Always a fleece “neckup”, also known as Turtle Fur and sometimes ear covers. They’re like ear muffs without the over the hair piece, so they work well under a helmet.
Feet were in long ragg wool socks stuffed into lined paddock boots: whatever I could find on sale when I wore out a pair. Socks ruched at top of boot or half chaps so no wind gaps.
Hands are the hardest for me as I have Reynauds. I’d either wear a thin glove under a leather thinsulate lined rancher type glove or a pimple glove under a wristlet. I don’t know what else to call it, but it’s a knitted fingerless glove that is long enough to cover the end of the jacket sleeve or tuck well inside it. Having the wrist covered was the key to warmth, and if I got too warm I could always push them towards my fingers to expose wrist. Instant cool down!
On the bitterest days, the only things I would add were chemical toe warmers. I would apply them on the outside of my socks at the ball of my foot and on the outside of the inner glove for my hands. Toasty! I hate the bulky hand warmers, but the toe warmers have a curved end that fits my palm well without interfering with my fingers, adhesive to keep them in place and they’re quite thin. I think they’re too hot directly on the skin, but work well with a glove or sock in between.
Best of luck to you. I salute your determination to ride through the winter up here in the dread north.