Ok, not quite a complete thing, but at least I found the perfect base for the concept. See Tank Chair.
Now, all that needs to be done is to mount a 20 gallon reservoir on there together with a turret mounted larger soaker (at least a CPS2500-calibre soaker) and enjoy! Just be sure not to run over any of your opponents when using it. That'd likely hurt! :goofy:
I want one! Granted, the builder's main focus is to help those with walk disabilities, but heck, the design looks purely awesome.