maybe im being dumb, i don't know a ton about towing, but...
what's wrong with towing a sled with a subaru? obviously towing a boat or something would require a truck but with something as like as a sled....
an sti has super stiff suspension, so its not gonna push the back end down too much. also, aren't snowmobiles, when on trailers, generally pretty centered over the trailers wheels? which would mean it would hardly push down on the hitch at all...
and lastly, a subaru will handle snow as well as, if not better than, a truck. unless you are talking about 2 ft + on the road, there is no reason a truck will be able to get to a trailhead better than a subaru and besides, if theres that much snow on the road, why not just park farther down and ride the sled up that?