Alright, I've done a bit more sketching. I think I'm gonna end up staying with this general shape for a side view. The wheel flares will not extend all the way over, so the coke-bottle shape will only be within the general front and back of the wheels. I'm thinking of using glass from the front of a super beetle because it's a little more rounded, and still easily available. It will also provide a bit more visibility. I only have the side and part of the front sketched up now, but I'll be adding more later. I'm not giving up on this just yet, although sometimes I get really put down about it. Got a lot of crap going on, so it's going to be hard.
I figure I will keep the front part of the frame: the front of the gas tank and cluster, to the doors, & part of the rear. If possible, I'm going to try and keep it no wider than the original bug, which means I'll probably have to gap the doors a bit wider to prevent some top looking down bottling. And I want to make special hubcaps, Like these (imaged from PelicanParts random vehicle thread) so I can avoid having closed front wheel wells that would widen the vehicle more. I'll upload a picture of the sketch once I've finished the front view and maybe the windows on the side. (still working those out, haha)
Sketch: (I need to do one to scale so that it fits. Looks like I'll be saving the sides of the bug, and maybe just chopping the roof and the part that covers the engine, and the tip of the front)