In the vein of this thread we also have been in a situation where our trailer has only been used one time, September last year, and none this year. We are hoping for better times for Patty's health and will be able to travel next spring.
The trailer was winterized last fall. The good side is the trailer sits in a very good insulated garage so it's out of the elements. I know the RV antifreeze does evaporate over time so the toilet bowl is probably dry. I was thinking of adding some more to keep the seal moist.
I was also going to run all of the electrical appliances, furnace and air conditioner to give them a little run time. What about hitching up, reinstalling the batteries and take it on the road for a few miles? Since it's been a year since it's last use I hate to see it sit for possibly another 8 months without anything being touched. I'm not sure if 10 or 15 miles is really beneficial though. They key is it is inside and dry so other than the tires and suspension being immobile, I think everything else is probably not in bad shape.
'04 Classic 30' S.O.,'03 GMC Savana 2500,'14 Honda CTX 700