[arcticdude]

That’s not a worry. The 12v pump has it’s own pressure switch to prevent that. Any over pressure will come from the city side.

You can do like I used to do with my 96- fill the tank. Close the fill valve and leave the city water on. Keep a 12v pump on to moderate the low pressure the city offered. Dump as needed.

I alternated pumps by switching as we left for a new trip. One pump worked for one trip. The other pump worked the next trip.

You are running a regulator on your fresh hose input, correct?