If anyone wants to work on this, please do. The simplest thing to do will be to base it on the design here: http://aerialroboticscompetition.org/downloads/killswitch.zip and then beef it up to handle the higher current that our vehicle uses. Basically, it just needs beefed up MOSFETS for the power side of it and the control side can be more or less the same. I'd say we need to design it to handle 120A@12VDC peak. The resulting circuit board should be as small as possible and preferably only two layers.