[trikkonceptz]

By far the coolest idea would be to drop a fifth wheel bracketed off the fron twin beam suspension, then use a pulley and belt system to power an independant alternator. Electrics would be a snap because the main fuse box is right there under the trunk lid. All it would have to be is a small rubber tire with a tension coil or small spring, hell even a small air shock or shock to keep it on the ground could make it work with little modification to the bug body.

Same idea different location;

Under the back seat, which normally rots away anyhow. If you cut out the floor there and make some brackets the idea could work there as well. The metal is coke can thin .. so it would not be much of a challenge for a good welder.