hey, my stampede dosent tip over. and thats doing 30mph power slides on-road with moabs . 12.5" wb, 13"with, 1 3/8 gc...... actually i was thinking about doing the same thing. although more of a buggy.
Do you have a stock chassis to use? Would be much lighter tht way. You could take out the diff and tranny and put an outrunner where the diff would be. I bet you could get the truck under 6lb rtr with that setup on 4s.
You could try something like this: http://www.hobbycity.com/hobbycity/s...less_Outrunner
Maybe have mtxmugen rewind it to ~180kv.