I have used a cap on my last two trucks. I have also used Roll N Lock and a fiberglass tonneau cover. The Roll N Lock was great for covering small things or using the open bed. I traded it for a cap to have more storage capacity. The cap works great for hauling a lot of stuff in a secure manner. I was able to remove it by myself and put it back on with help from DW.
I use a Thule rack on the roof of the truck for my kayaks. It creates much needed space between the camper and the kayaks with a 5'5" bed.
The only concern would be payload capacity. The cap will use up a couple hundred pounds that could be a problem with a half ton truck.
Also, both of my caps had carpeted interiors. With the windows open it is more than comfortable inside.