I've been RV'ing since 1957, that was well before most RV's had indoor plumbing. I have yet to have a problem with a plug in anything I've ever owned.
1. I use any TP we have in the house.
2. Never leave the tank valves open although if I was going to use the washer I'd open the grey tank.
3. I never empty the tanks till at least half full, even if I have to add water.
4. Use the correct chemicals. I use one that has coconut oil in it and I have yet to need to replace a dump valve or even a toilet bowl seal.
2009 45' Magna 630 w/Cummins ISX 650 HP/1950 Lbs Ft
Charter Good Sam Lifetime Member, FMCA, SKP
RV'ing since 1957, NRA Benefactor Life, towing '05 Odyssey