Honestly, keeping a chestnut clean during the winter isn’t much more work than keeping a chestnut clean during show season (all bets are off with grays!!!).
Good nutrition = shiny, glossy coat (even in the winter!), so the majority of the mud and dirt just slides right off. If he does manage to get muddy during turnout, I let him dry off and then grab the curry comb. A pass with the vacuum gets the worst of the gunk off, and then I’ll finish with a flick brush.
My boy is a TB with a wimpy winter coat, so blanketing is a must - I may have to send his blankets off to the cleaners a few times in the winter, but at least he stays clean underneath! He’s not body clipped, but I still keep up with trimming long hairs around his fetlocks, jaw, bridle path, etc. (same with mane and tail pulling).
If his paddock is really sloppy, I’ll put his tail up in a mud knot, but I’ll take it down when things dry out because he tends to rub at the knot!
If we ride in a clinic with a BNT, I’ll pull out the spot remover (Carr, Day and Martin makes a fabulous spray) and make sure his socks gleam. Right before we go into the ring, I’ll spritz a little Dream Coat on a sheepskin mitt and swipe it over his neck, shoulders, and bum for a little extra gleam.
We’ve gotten lots of compliments on how well he is turned out, even though he lives outside except for absolutely foul weather - I guess we’re doing something right!