I do like the way that you are using multiple materials and your use of fiberglass has actually gotten me thinking about incorporating it possibly. I do think that fiberglassing the side rails and bonding the whole thing together with epoxy would be your best bet. Your frame would be indestructible. Also for all the naysayers, oak is much less dense than aluminum and stronger as well for the weight so go for it. I hope you guys get a chance to prototype this and post it up on here. Maybe we should see who has a prototype frame done first
