Most batter drills come with a few spaire batterys aswell, you might even be able to fit the drill to your leisure battery some how
I've tried that with an 18v Bosch screwdriver/drill. I bought a nut runner attachment but found it very uncomfortable as I didn't have enough hands the hold the reel, hold and operate the drill and guide the hose onto the reel. I didn't have the hose reel fixed to the van floor. To make using a drill a little easier, the hose reels really need to be fixed to the van's floor and in my case fitted through rollers like Tim has done.
The other issue is that for a 2 man system you need quite a bit of space between the hose reels to accommodate the length of the drill.