Actually, the term "cap" all depends on location. You might call it a cap where you are, called a topper here. Hence the local shop, TopperTown. Just to show it's not merely my opinion, take a look at the website below to what they refer to as a cap:

Undercover Tonneau Covers: Hard Truck Bed Cap at Carolina Classic Trucks

I have no problem with toppers. Had two different trucks with them. They're great for throwing in fishing gear, and tall items. Where they suck is when trying to put a boat trailer down a ramp and needing to SEE where the center of the trailer is in reference to the center of the boat. Side mirrors don't help with that.

I also have towed small utility trailers for tens of thousands of miles. The small trailers are handy, but just about disappear behind a truck. By the time you can see one in a side mirror when backing up, it's already starting to jack knife. If I can see it out the back window, I can park it anywhere.

My larger 25' travel trailer is easy to back. Obviously the only thing that can be seen out the rear window is a big white camper. The side mirrors work perfectly for this job.

Not trying to sell anyone on this idea that already has a working solution... but if the OP is having second thoughts about having to lift a hard cover off to use full advantage of the truck bed, the roll up cover might be a good alternative. About the same price as a hard cover in my area.

 

Ice and snow... Hmmm, that's the white stuff, right?

I'm in Central FL. The only ice here goes in blenders.

 

Had a snug top on my last truck. Opted for a Leer on my 2011 s/crew. Snug top was top of line but so was the price. Bought a Leer 100XQ new in Portland, Oregon a couple of weeks ago. Price was about 1750.00 with slider, and electric locking canopy (wired to my truck remote). new SnugTop would have set me back about 2400.00. So far liking the Leer just fine. No cracks, no leaks.
Good luck. Ken