Talk to the folks at Rebirthauto. They actually build an adaptor that uses the belt. I believe they use that dual motor setup in one of their Bugs. I'd say that there would be no trouble at all using those huge belts. Check out the video at the bottom of the page.
http://rebirthauto.com/ra-vwsa-twin.aspx
Pete
http://rebirthauto.com/ra-vwsa-twin.aspx
Pete