I think that sounds like a great idea. I have been thinking of making a roof myself. The GTRV roofs work kind of like that.They have a fiberglass part the goes over the van roof and makes it stronger and then the raised roof mounts to that. Good Luck and take pictures.
2008 Ford E-350 V-10 EB
U-Joint Off Road 4x4 kit in the garage
2004 F-350 Dana 60