If you're bashing it, maybe consider the extended wheelbase rear arms from Traxxas (the stock rear arms on the Summit). Extends the wheelbase by 10mm.

Get a larger set of wheels, maybe stock wheels from a Thunder Tiger MT4 G3. Light but very bashable. I really like the Trencher X's on 1/2" offset Desperado wheels. Some people don't like to run wheels too heavy, the Trenchers are about as heavy as I would suggest.

Shimming the diffs is another idea if you want to really tear it down. otherwise, save that project for when one blows up.