The bespoke cover for my 19ft toy hauler weighed over 100lbs, maybe 150lbs, of weight that behaved like trying to force a corpse into a driver's seat(long story for later
).
Had to haul it up the ladder over my shoulder(the cover, not the corpse{OK, ONE corpse just once... }) until I installed the removable engine hoist(which was 40lbs of rigormortis'd except for the ball bearing swivels, octopus)
Then had to dance around vents and solar and antennas and cable while dragging the cover across all of those and throwing part of it over the edge in a narrowly defined space and shape. I never tried it in the wind or rain or dark but I'm sure the fun is compounded.
Loved it.
You better be in really good shape, have a good attitude and funds to hire a sailmaker when the stuff on the roof tears it.
As for protection:
Getting into the trailer if you don't have a bespoke is a pain since the door is covered and the slop in the fit will not let you get the door open and squeeze in. You get to uncover it to check what needs checked.
Mine didn't because it was sunbrella, but a cheap one will not last two seasons in some climates.
Mine didn't because it was in Havasu, but I'm thinking it might be a fine way to get mildew not only inside the coach as some say they get due to weather, but maybe a nice outside fur also.
A cover vs hail is about as much protection as a hanky against a hammer attack, and I don't know if ice on a cover would be any different than ice on the rv.
And some of them will beat the paint right off of the coach.
And some of them will cause permanent streaking of the coach finish.
And you get to crawl under it in four or so places to stretch ties under it from side to side.
Others will disagree.
(unless you're talking about a stand alone drive under aluminum, not quite a shed, cover.)