I say go for it. I saw a Toyota pick-up with what looked to be stock camper/sleeper on the back.
It looked like it would be a blast to own. I see no reason why you shouldn't do it up! Just make sure you take plenty of pics and detail your project for us.
I'm going to buy a cap sometime before winter, I really miss it, now that I don't have one. Sure it's handy to have such quick access to the truckbed, but there is something about having a cap, and then a small mattress, some pillows/blankets, and a cooler that I just love.
Hell yeah for the pimped out camper shell.
Just for the sake of sharing such a good deal - I found on sale last weekend, a 400 watt power inverter with 2 outlets for $35 CDN. It was half off. That'd be something you could think about getting. Though I'd guess with a camper, it'd have it's own battery/power supply.