Put something quiet like a fuel cell setup on it, load it down with gear, and tell it to follow the guy in front of it. The return of the pack mule without the easy refueling.

Put a hundred out in the battlefield, hobbling their way back and forth across the area. If anyone shoots one, log the location and flag it for attention. If someone interferes with it or moves near it, have it uplink video as long as it can. In the meantime, use it to carry supplies where needed, with proper randomization routines that make it infeasible for the enemy to follow without being seen by another M.U.L.E.
Remember the idea I suggested a few weeks ago about flooding a country w/ observer bots? This could be a good start, it'll eventually turn into a real mountain-goat.