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.
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2008 Ford E-350 V-10 EB
Transformer Interior
U-Joint Off Road 4x4 kit in the garage
2004 F-350 Dana 60
My GTRV pop top is super strong I can walk all over it. U could even build a front storage area like the westfalia tops I had such an open storage area on my 76 vw westie I miss having that space.