I never followed up on the company's response, since I already spent my "toy" money on a core aerator, a spare attachment plate, and a towing adaptor. Will post pictures of my adaption in another thread (or resurrected thread) when I get a chance to break out my camera.
Following JJ's recommendation (he's purchased from Gaetan) I contacted him about possibly modifying his smallest thumb to fit. But, due to email problems and his vacation schedule, I ended up buying the thumb off eBay before Gaetan could get his design finalized and emailed to me. Last I heard, his thumb was about $250 US, plus shipping from Ontario.