Team 36, have you considered a chassis protector? Andy on here can turn these around quickly and are of exceptional quality. He can provide them as just a clear stone protection layer which is a thicker vinyl providing most protection, and then if you want to bling your chassis a little, he can do nice carbon effect layers to cover the clear. These cover all the areas an undertray would and are a very popular choice. All screw holes are also pre cut.
His profile page: -
http://www.oople.com/forums/member.php?u=7394
The post in the Team Durango section with pics: -
http://www.oople.com/forums/showthread.php?t=95202
Daz.