The law is probably different in Sunny California, but when I boondock, the gray water is not retained, except for the last day. The rest goes to water the bushes.
I dunno what some folks put down their sink drains, as they will claim their gray water stinks. I've never had that issue, and I consider myself pretty sensitive to stink.
Extra fresh water, a bladder or two in your bed should be no problem with the 5r over top of it, with that nice rig of yours, payload shouldn't be an issue. maybe two 60 gallon bladders on either side of the hitch?
