I do raise mine off the ground on 5 points: jack stands near the axle, tongue jack, and rear stabilizers. Modern radial
tires do not develop flat spots, but
Scamp and torsion axle manufacturers recommend the practice. Aside from that, I like how solid the trailer feels. I use it as an extra office when I need a quiet retreat.
For the snow load at your latitude, I'd do two things. (1) Add floor-to-ceiling braces inside. 2x4's with squares of plywood top and bottom should do it. (2) Remove snow during and after major snow events. Powdery snow is not a problem, but heavy wet snow and/or accumulated old snow that partly melts and refreezes is bad.
If humidity is a problem, remove cushions and fabrics and use a chemical desiccant to keep mildew at bay.
Drain the water system and put a gallon of RV antifreeze in the tank. Pour a little in the sink drain to protect the trap.
Somehow you need to keep the
battery charged. Since I don't have power at my trailer, I remove the
battery and keep it on a smart charger/maintainer is a storage room.
Most important, inspect inside the trailer regularly. If a leak opens or critters get inside, the sooner you find out the less damage is done.