Thanks for all the encouraging words you guys. SmallHaul Scott captured a nice video of one of these machines at our steam show this past August.
http://www.youtube.com/user/SmallHau.../1/RRxBpOnc3pw
Travis, The way it can wiggle side to side should give decent traction. I'm real skeptical about the original hard rubber tires but they're going to be tried before I change them. I may have to set them up in the mill and cut some relief in the lugs like pulling tractor tires. As far as weight, I'll play that by ear. The thing is pretty heavy already. I don't know what battery setup I'll need yet. I'm looking for about 12v.