I am in the process of converting a Ford e350 into a camper and I added a poptop. I experimented with different designs and always found myself going back to the hinged pop for simplicity and stability for making it yourself in your garage.
I cut the fiberglass roof of the van and added a raised wood trim around the hole for mounting purposes and keeping water out. Then I ordered some high tech cloth like sunbrella that breaths but is water proof. I build the roof portion and hinged it from a piano hinge on the end. the top stays up with a piece of ply that folds up when the top is popped and keeps it upright. Hardest part was sewing the fabric and fitting it to the opening, but it turned out on the first shot. Must have been beginners luck. Everything is epoxied and I haven't had any leaks
since I did it a year ago. The only advantage I had was steel supports welded across the roof for safety. Those gave me a fixed structure to mount to.
I recently purchased a 13' scamp
so unfortunately my progress on this project has slowed, but it should be a pretty sweet "Poor Man's" Sportsmobile if I ever get it done. The bonus of going low tech as well is that you can repair it with anything at a hardware store vs machined parts from a company. You could always think about something like this. The scariest part is cutting the roof. I stared at it for days before I grew a pair and had at it. Seems like a bad idea at first, but I'm really glad it's there now.