I think the talk about paint and/or decals being damaged by covers is an urban myth.
I don't recall anyone talking about that first hand, but rather thy read, or heard about it.
One good tip is to cut slits in tennis balls and put them on the gutter extensions. It will keep the extensions from cutting the corners of the cover.
Our cover is actually designed for a motor home longer than our trailer (by almost 6 feet) so I have to roll the excess up and tie it on the tongue, and it doesn't have a zipper door, which I wish it did, but I got it for $126.00, so I'm not going to complain much.:) I can actually loosen the tie rope and there is enough room to squeeze into the trailer if I have to.
This will be the 4th year (second trailer for it) and it's still fine.
We cover ours because where we have to park it is under trees, and I like the extra (double fabric in the roof) protection from small branches, ice dropping, etc.
Experience is that which you gain immediately after you actually needed it.
2011 29' Kingsport 28RLS by Gulfstream
2013 Ford F150 Ecoboost 4X4 Supercrew