Mine is indoor stored also. Makes a huge difference in natural ageing & need frequency of waxing needed to keep that almost new look.
With the exception of the front cap, the whole trailer gets the full treatment only once a year & that is in the fall before going into winter hibernation.
The treatment starts with a top to bottom wash. Once clean the roof gets a wipedown with 303 protectant, not cheap. Front cap gets 3M cleaner wax to remove any bug remains stains then the whole trailer gets Meguiares Flagship waxed, not cheap but lasts longer than anything else tried over my boat maintenance years. This is NOT a one step cleaner wax. It does not remove stains or chalking. That is what the 3M is for.
The last step is the detailing going around the seals with 303 or a specific product for seals. Shortly after, into storage it goes. Next spring it gets a washing with little non wax removing soap to get rid of storage dust, & maybe a roof freshening with 303, perhaps another coat of Flagship on the front cap, & we are good till the following September except for a couple of front cap cleanings & waxings if I get a chance.
This annual cleaning & waxing is a multi day effort, usually with the help of the DW also, but the result is a trailer that looks only a year or so old & not the 11 years that it is with over 1500 nights on the road & 100,000 miles behind it.
If you want to keep your unit looking good there is no easy magic one step way of doing it no matter what the product labels say. You will get the product performance that you pay for. They all require about the same labour to use. The really good pure wax or sealer ones will last much longer than the multi purpose cleaner waxes.
What is your time worth?