Just purchased a roll-up cover for our Chevy 3500 long bed from Toneau Pro. Sits about an inch above the bed rails. I can easily roll it up myself to the rear window of the cab when towing so have full access to the entire bed, and roll it back down when unhitched. It latches at the end of the bed, so if you have a locking tailgate (which I don't) it will give you some protection from theft. Total cost was around $290 or so, and installed very easily with clamps (no drilling). There are a bunch of companies who make this type of cover, and I have no opinion to offer as to which might be better. What we have works for us, though, and with a price tag under $300, I figured I could replace it in 5 years or so if I should have problems with the mechanics, fading, etc.