i think the problem is you're using your equipment beyond it's designed capacity.

tents and sleeping bags and inflatable pads really are not meant for year-round use.
the construction and materials and chosen for the average camper, plus a little more.

you want to live in a tent year round by choice, then your choice of equipment should
reflect that decision. you're gonna need heavy-duty, heavy-weight gear.

good news is plenty of useful gear is available for cheap at army surplus outlets.
hoo-rah!