Thanks for all the interesting suggestions... If only I knew a snowmobiler! It sounds like breaking in a trail all by myself won't be happening. Cross-country skiing is probably just about the only other sport I think comes close to cycling for the combination of fun and fitness, although I know one guy who swears by speed-skating.
The weather turned foul in a hurry here, and we've already had our first bit of snow on the ground for almost 2 weeks now. I put my new Nokian studded tires on. Way too early! I've been on the trainer, it's not so bad (yet). Once winter really gets here, I'm hoping to discover some 'ice-biker' haunts on our riverside trails. I think that there will probably be enough joggers and dog-walkers that people in search of pristine ski-trails will go further afield.