There are a lot of people doing this. It look like people jsut use the bumper that they have laying around. I also plan on doing this with my buggybut will probably get the slash front and rear bumpers for it.

http://www.rcuniverse.com/forum/m_8177558/tm.htm

http://www.rcuniverse.com/forum/m_8176932/tm.htm

http://www.rcuniverse.com/forum/m_8155863/tm.htm