Chevrolet Forum - Chevy Enthusiasts Forums - Hard top bed covers ?'s on Peragon /retrax

Hi I'm new to the forum and I was wondering members advice on hard top bedcovers. I've been looking at several and narrowed down to retrax and the peragon aluminum bed covers, I think. I like that both do not obstruct back window when open. I like the idea of the no canister with peragon and also the cost difference, but have some questions.
1.)How much space between the bed floor and a folded up peragon is there? How wide is this from back of cab bed towards tailgate? I'm wondering because it looks like if something slides towards back of cab you might not be able to open the peragon.
2.) if the peragon cover is wet, how do you keep water from draining into bed when opening? Is this much of an issue?
3.) can you put any weight on either peragon or retrax?
4.) can you put load bars over the covers, i.e. Thule with some adapter in the stark holes OR bed ladder/cargo rack?
Oh, I have a black 2012 Chevy 4wd crew cab. I'm looking to keep a few tools, containers with paperwork (flyers, promotional info), etc out of the cab and secure since I travel and want to keep thing neat and clean, also something easy to remove if needed to carry larger items.