You say it's stored in a "storage yard". Is the TT covered when in storage? If so, then solar isn't going to help you keep the battery charged while in storage. In that case, I would look into the trickle charger.
Will the storage yard let you plug into to shore power for a couple days before you take it out of storage? If so, you could stop by on day 1 and plug it in to shore power, then stop by on day 2 and start the fridge, then on day 3 go RVing. That will charge the battery and get the fridge cold before your trip. And if all you're doing is charging the battery and turning on the fridge, you're not using a lot of the storage yard's electricity.
