Help Identifying Parts

[Exsys]

The first picture is of the shroud around the black water tank. Is that a duct from the furnace keeping the black water tank from freezing?

Is the part in the next picture a water pressure regulator? Is it necessary to have that? Can I remove it without any problems?

I also noticed there is a white access "tray" on the curb side of the trailer for filling the fresh water tank. Isn't there a way to connect a hose to the water supply in the back and open a valve to fill the tank?

[idroba]

First question: Yes, looks like the heat for the tanks
Second question: You can eliminate it but if you are in a campground with high water pressure you could potentially have some overpressure issues. I will admit to removing mine in both my Argosy's. You can add an external regulator if you get into a high pressure situation.
Third question: Some '60's AS had a valve to fill the fresh water tank from the city water hookup, but by the 70's they were eliminated. Two reasons: people tended to leave them on and overfill and damage the fresh water tank, and there is a potential cross contamination of the water tank becoming connected to the city water input which is a code violation.

[Exsys]

Thank you idroba. I plan on completely gutting the plumbing and replacing all of the copper with PEX and simplifying the supply lines. I don't plan on using the fresh water tank so it is not an issue for me.