You might consider getting shoes with ice studs, a snowball rim pad to keep from snow/ice buildup. This is contrary to the boot thinking, but much less work for owner, no chances of rubbing, than boots are.
Ice studs are actually pretty minimal BUT provide good traction on any surface. These are the drive-in studs with wear collars, over plain little drive-in traction studs. The snowball rim pads leave the sole area open for cleaning of mud, frequent application of Durasole as suggested above.
I am iffy on the Trimmer, getting someone different. Trimmers are not nessesarily Farriers. She was remorseful about OPs short trim 2 years ago, but is not applying that lesson to other horses she currently does. Anyone doing barefoot horses SHOULD have learned to leave hoof a fraction longer, remove minimal sole, to protect the working hoof being worn down. Short (NOT EVER SORE) walls are done to compensate for added shoe length to hoof and expected growth before getting new shoes again. Not the same trim that should be done to a horse going barefoot. Sole should also be left thicker as protection, on shod horses who can step on rocks or other pointy things shoe doesn’t protect from. Sole should NEVER be so thin you can press into it!
Worth mentioning is time horse is stalled to dry hooves out from being wet in snow or mud. Wet footing softens hoof/sole to feel even more on rough ground. Our horses come in for the night, lets hooves dry, skin above dry, to help prevent various problems for the horse.