Try on a spare water pump, and mount it where you can wire & plumb it w/out having to R&R the old one. My coach came w/the new fangled quiet 65psi ShurFlo pump. I had a spare I carry when going to Baja (nowhere to buy one there w/out a multi-day trip to the States. For fun I mounted it on the coach frame next to the OEM pump. Whadaya know. For once in my life I was right. On the way to a week outing w/other knucklehead motorhomers, pump shut off failed & pump ran full time for hours & wouldn't shut off (got really hot too). Takes about 10min. to change over from P1 to P2 and I'm back in biz. Now I have the new ShurFlo installed (3 year no questions exchange warranty, woo hoo) & back in biz, again.
Also, try whole-house RO: Vagabond RO System
sized for a motorhome or 5er. You fill coach tank w/fabulous water wherever you are. Fill rate is a bit slow if city pressure isn't great, so I added a an RO Booster Pump
for 20+ gph fill rate even @ 25psi city water in Mexico. Best thing I've added for my coach period.
How about House/Chassis battery gauges, to tell at a glance whuzup w/charging:
Note how chassis volts are lower than house- at a glance I know chassis isn't charging. Neat. A pair of Radio Shack 22-410
analog gauges work great (I checked out digital types but the needle type are easier to read the disparity).