Re: water pump
When figuring GPM, also figure how many people will be in the bus. A low GPM pump might be great for solo travels, but not so great if someone might turn on the kitchen faucet while you are trying to shower. In our old house, a call of "Here comes the hot!" before a toilet flush would warn bathers in advance of a loss of cold water pressure. I'm just sayin' . . . .
Also, I can't picture running a washing machine or dishwasher off of one's tanks, but saving the loads for when you are hooked to campground/city water pressure and drainage, where the pump size wouldn't matter, anyway. But as always, YMMV.
Someone said "Making good decisions comes from experience, experience comes from bad decisions." I say there are three kinds of people: those who learn from their mistakes, those who learn from the mistakes of others, and those who never learn.