We, too, rarely remove our TC much any more, and also in the recent past have not used it much over the winter. I try to run the generator monthly with an electric heater on, for an hour, to exercise it. I also start up the diesel for a bit. We have a little battery maintainer to keep the truck batteries up, the TC is plugged into shore power.
So far all has been well. I sometimes start the hot water heater and the furnace etc. We use the TC as our guest house occasionally, which also is good for keeping everything exercised. Be sure to check the tire pressure after it has been stored. We did have a brake line that failed(rusted out) When I started the truck for our first outing the brake warning light came on and the pedal went to the floor. I replaced all of the 10 year old the brake lines then.