When you're renovating your RV you need to understand that the piping and plumbing is different than your typical home. I went to Home Depot with some fixtures from my RV and the guy say, "Oh, this is RV plumbing. Yeah RV mean 'weird!'" That ended up being the case most of the time with no matter who I talked to.
That's not to say that you should be afraid of renovating just because the RV piping and plumbing is different. You just need to be aware so you can plan accordingly.
In this video you'll see that we had several plumbing issues that were interconnected and took us a while to isolate and then fix. That's just how it goes with an RV. It seems like your repairs are ongoing. Be patient with you and your rig.
Our RV Renovation Plumbing Project
With our rig, we were changing the piping of our shower. We couldn't find a shower pan that would fit where the current drain was so we had to order a new pan. That meant moving the drain from one place to another.
KEY TIP: At Home Depot they have these sink drain kits. It has most of all the pieces you'll need for piping especially for an RV since sink drain sizes fits most RV piping. Grab one and try it!
We used the elements from the kit to move our drain but we had problems with the connections. We had leaking under our shower into the compartment underneath. That lead to tearing up the floor again and adjusting the shower drain.
Later on, when the leaking continued, we realized that the issue was actually in the hot/cold connections with our sink.
Hopefully our RV renovation piping experience will help you figure out your RV renovation or leak problem. Good luck!