After you get it back together, Change fuel filter 3,000 miles for first 9,000 miles. Crud might be working loose as rv is getting used again. Some crud is almost impossible to get out of tank. But will break up as you use rv. Carry spare filter and everything you need to change in middle of nowhere.
Don't know where you are but if close to commercial fishing boats see if you can find out who cleans those fuel tanks. Marine environment really is hard on those tanks and those type mechanics know how to really clean those tanks out.
If RV sat for a long time before you bought, I would change all fluids.