I’ve owned 2 truck campers over the years.
What I didn’t like:
1. No awning to get out of the elements (but stay outside) - so carting along a shelter for outside cooking/eating is a nuisance.
2. The steps on most campers are terrible - narrow, and when wet are slippery. Slips/falls are a big risk. There are some campers with nice, wide steps.
3. The wet baths are a nuisance.
4. Bathrooms are for skinny little people.
5. Minimal storage.
6. Small fridge for longer trips
What I did like:
1. Truck rode really smooth with camper
2. Could get into spots where you couldn’t with travel trailer/fifth wheel RV
Other considerations;
1. If trailering with camper - make sure you buy a proper hitch extension set-up like Torklift Superhitch:
https://www.torklift.com/automotive/...eries-overview
2. Definitely buy proper camper tie-downs:
https://www.torklift.com/rv/original-fastguns
Yes, you should use a rubber bed mat under camper - protects the box and minimize sliding.
Storage off the truck - I used an old hay wagon but make sure you have solid/stable sawhorses or something that will support the weight