A couple of ideas
I had an extended cab Ford and I built a platform that ran the width of the cab and went from the back of the front seat to the back of the cab. I had it set up so that it could be put up as needed so you could set something like that up once in camp. That way you could provide a comfortable. cozy spot for your daughter and the two of you sleep in the camper. Careful though, if your wife and daughter get mad at you, it may be you sleeping in the, then, not so comfy, cozy cab bed.
I have a shell on my current Ford, 1971 F 250 4X4 standard cab (only cab back then) and my wife and I sleep comfortably in the back and we have three dogs that sleep with us but my bed is 6' wide and 7' long so there is plenty of room. If you can afford an actual camper you will probably find that you will use it more since all of you will be more comfortable when travelling. If you do go that way, check out Phoenix or Four Wheel campers. A camper with a collapsible top will do you a lot better when in the back country.
Also, a shell that is a bit taller than the cab is a lot nicer if you go with the shell. I have my bed at the height of the bed of the truck and I still have room to sit up in bed and read, etc. My bed is made in a way that I can simply reduce the length and then have room to stoop/stand when getting dressed. I really don't like dressing while laying down. Thirty years ago, not so bad but now, no thank you.
Mikey