I'm nuts for any dual-use tranforming vehicles or vessels, and here is a good one.

http://www.britishpathe.com/video/army-river-crossing

WW2? British army system of using covered truck, its side-boards, some tarps, litters and odds and ends to construct both a "pilot boat"/canoe and a barge able to float a Jeep!

The pilot boat carries about 3 guys and a line to the far shore and then they pull the Jeep, crew and wounded across.


I bet if they had two trucks they just might be able to build two barges and have each barge support one axle and float whole trucks across.

 

dual barging the truck across would be a good way to lose it in the river. It would either mean having the sides between the barges low enough to risk water spilling over, and then you're screwed once that starts, or so high that you're at serious risk of rolling it.

Would be far better to go full canvas skirting, along the lines of the DD-Tanks used at Normandy.