Hello, though new to this forum, I've owned popup campers for over 22 years. The first was a custom made Hallmark 8' Victor w/ full bath for a shortbed truck, then a Hallmark Cuchara in 2000.
I hope you find my conversion interesting.
A couple months back I bought a used FWC Kestrel shell (found through this forum, thank you) to mount on my '09 Silverado std bed 2500 crewcab. Though the common thought is to find a Hawk and tie it down, the Kestrel was exactly what I was looking for, as the truck serves as a multi-purpose platform.
The truck has a LoadnGo removeable toolbox/bed which I forklift on/off with the intregaled fork pockets.
The plan from the beginning was to make a metal pallet base for the Kestrel that allowed the quick exchange of work box to camper.
The base is not attached to the camper, rather the base has a seriies of tabs that align it with the camper when lifted. The reason for this was not to have extra weight hanging from the camper if it was off the truck sitting on camper jacks. Without the jacks, the camper stores on the pallet base.
The following photos are after the original fitting and after having the base powder coated. The first exchange of the camper to the work box took less than 1 hour including the time to release the turnbuckles and mount the box's tiedown and take photos. I believe in real complete worktime with setup and cleanup.
This pics are the basic fitting. Turnbuckles have been replaced with qwik loads. With the removal of the camper jacks and use of the qwik loads, I expect the exchange tine to get down to around 30 minutes, by myself. 
