Adrian, please explain further. 12th scale doesn't encounter bumps like an offroad vehicle would. Our bumpsteer is minimal at best. You are saying our bumpersteer gives a toe in. I could see that during a turn, the outside front suspension compresses a little causing the tire to turn in a little more, but that would feel nearly the same every time.
BTW, have you found any servo mounts that will work for mounting flat? I really don't want to use servo tape and/or superglue.