I towed my chassis home from the welder today. It towed very well except for being a bit bouncy. I understand that this will take care of itself when the cabin is attached. The chassis looks pretty little but my cabin will hang over both ends just a bit to allow for the curve on the bottom of the cabin. I had the welder add a bunch of angle brackets to bolt the floor down, and plates in the structural worry zones (Grant's suggestion). My tires turned out to be just the right height for the tow ball on the car. It rides pretty level. So far so good.

Thanks to everyone who has helped me get this far.
Kris