Darkseid,
If the open drive train becomes an issue, I may just have to use some of that clear plastic film they use on the off road cars to keep the chassis from getting scratched. I'll just make the holes in it smaller than the cutouts. That way, I have the clearance needed, but still have smaller holes to keep out the gravel and etc. It will be interesting to see if I will need additional motor cooling if I do it.