Moving the links inboard is a good idea, welcome to the world of crawling where tinkering and tweaking is the order of the day instead of running what the manufacturer provides for you.
As for bodies, take your pick from the many crawler shells around. The
Kamtec Baja is popular, the rounded roof means it has a better chance of rolling back onto its wheels when it rolls over. There are bodies from
JConcepts and
Axial and Proline that all fit.
My Berg runs a JConcepts Stage Killah. If you are getting into serious competition there is a good chance you will replace the chassis to convert it to a bodiless crawler with the Warthog, Aluminati or Beetlejuice chassis.