Quick Additional Note

One thing I meant to note about the deconstruction of the rear end of the trailer, because others might find this information useful, is that the first thing I attempted to take out was the tub. But I met severe resistance when trying to use the special drain wrench to turn the drain out of the cast p-trap. A previous owner had put a huge amount of silicone caulk around the drain, but I was able to cut that out fairly easily. So I became worried that someone had used permanent adhesive to attach the drain to the cast trap, and that I would have to break the trap, or worse, break the tub, in order to remove it.

But, as is often the case, my good Airstream buddy Frank gave me the perfect piece of advice. He told me, "Rookie, what you need to do is get a heat gun pointed at the drain/trap junction from below, and then hit it with the wrench from above." Since I have such a handy and convenient rotten hole through the floor, right under the tub, I was able to perform both operations from the top-side myself. And sure enough, after about 20-30 seconds of heat, I torqued on the drain one more time with the drain wrench, and it easily turned all the way out. I used a very low-heat heat gun, but it would also be a good idea to use something to shield the fiberglass around the drain if your heat gun is quite hot.

So, thanks Frank!