Thought to consider on supply? Most parts of an RV are repurposed from other uses where they can be quite common. That issue of being common can make it much better to use stock parts rather than RV parts! Both for ease of getting them in hand as well as pricing.
If you can get a piece of that tube out with the number/letters on the side to ID it, there is a pretty good chance you can walk it in to any plumbing supply house to match it, saving on price as well as any shipping involved?
No guarantee it works but that does look like a hot tub part from here!