Here in the damp-damp East, a cover will trap moisture that is normally blown away if not covered. Increased water equals more rust, and electrical component failure. Don't do it. While we are at it, remove the cover from your home air conditioner.
I bought an AC cover when I first got my TT last year, but then decided to buy an ADCO total TT cover.. Keeps the sun off when not using it to keep the finish shiny and decals bright and the ice and snow and dirt off in the winter.. For $250 and 3-5 years use before it wears out, small price to pay to keep the TT looking new for years. I use the TT totally less than 2 months out of 12.. so needs protection..I still put the AC cover on before my big cover to soften the sharp edges of the roof unit to protect the cover from tearing.. So at about 25 bucks... worth it! Also.. get tire covers..
Tim, Ramona and dog Scruffy 1982 Coleman Sun Valley PUP (retired) 2014 Keystone Bullet 285RLS Ultralite TT 2013 Ford Expedition XLT 5.4L Triton V8 Equalizer E2 hitch
I had an old motorhome that lived it's whole life outside, I put new A/C units on in 2008, when we sold it in July, 2015, all you had to do was brush up against the A/C units, and the plastic would crumble. The UV does bad things to plastic, I think covering anything plastic on the roof would increase its longevity.
I cover mine in the Fall to keep leaves out, and through Winter to keep snow from packing in. I don't think snow would matter, but it is the thaw/freeze cycles that would be my concern. I leave a little space open on the rear bottom to allow some vent.
I'm also curious on others thoughts, as I don't see many others with covers on them.