Sorry.. Been a LONG time since I've been through.. Never did get around to building that alternative box.. Ended up selling the RX8 and getting a Challenger.. Dropped the 8" tube off on Craigslist..
Stitching a tire.. It's about as easy as it sounds.. Stitch it with stainless wire, rubber cement a rubber liner over the stitching on the inside and put a tube in it.. I wouldn't trust 'em on the road, but if you've got a mud truck that runs 10 - 13psi in the tires it'll do the trick..
Other things.. What's in the dash..