Large area of woods, some cabins/sheds for storing the equipment and housing WiFi connections. Obviously a few stockloads of water warfare general equipment. (Everything from your typical CPS's to WBL's and APH's.) Should have a decent lake with rowboats and pedalboats for naval warfare training.
The water piping system should be well suited, with strategically distributed faucets around the cabins and even in the woods. System should give enough power to charge SC's/Speedloaders and to outrange a CPS 2000 from a VHS. The whole place should be located near a hardware store, but perhaps have a store of it's own.
Basically, this is a better version of Camp Water Warfare, but in order to train for water warfare, you need a wide variety of environments to play in where possible. I would say that the cabins could even be setup a bit like a neighborhood, given how common of a playing environment it is.
Definitely need a WBL target range, as well as a smaller blaster/streams range, which should feature moving/dodging targets and hit detection systems to score players' shooting. Definitely would be good to setup a target shooting course as well (Think CoD or CounterStrike GO training course), one indoors and one out, using the same dodging targets which are kept off course and out of easy soaking range. A water balloon throwing practice area would be good too.
Of course, none of the fancy targeting stuff is needed if there's always plenty of people around camp to train with.