We trained on the M353 when I was in Motor Transport School in Missouri. The instructors told me it was a generator trailer. I spent at least two weeks working with them, and I had this novel idea of adapting it with a wood deck for hauling a M274 Mule, or possibly motorcycles.
Currently, there are guys out there getting thier hands on the not too common M116A2 (M101 series trailer, flatbed generator trailer with surge brakes) and doing some extensive work to convert them to haul a M274.
The drawbacks are: You hack up the body, you have to make or buy large tall loading ramps, driving the Mule up is quite a hairy task, once loaded it barely fits even still, and the center of gravity is quite high when loaded.
While all of these are disadvantages on an M116A2 converted to haul a Mule, I suspect that NONE of them would exist when an M353 is converted to haul a Mule. It's larger, so no or little body work will be done (there are two support brackets that *MAY* be in the way. While the M353 uses 2.5 ton wheels, the deck is below the axle, thus shorter ramps would be needed. And loading the Mule will be easier. And the ceter of gravity will be at or below the center of the axle, thus towing will be an ease, and the trailer will certainly handle better. Due to it's larger size, the mule will fit nicely between the fenders and the front frame, unlike on the M116A2 where it's riding ontop of the thing.
Anyhow, that's my little speil. I just bought an M353 and I intend to convert it to haul a M274 Mule. With a GWV of 2,650 lbs it shouldn't be a chore to haul even behind a civilian truck. Furthermore, if in a highway collision, the M353 will protect it's cargo better than an M116A2, which would likely loose it's cargo.