find your bumper-box lid, and put it in place...flip it open, and make sure that the hose or cable isn't going to interfere. might need to move it up a little higher.
I haven't decided the exact locations of mine, yet, either. One other possibility I keep kicking around is to put the water inlet just aft of the street-side wheel well, kind of like in Joe's pic, only lower. (Joe, you must have a different arrangement inside; those spots would put the pipe/cable in my bed! the top part, where I put myself...not the bottom part where I put my clothes.
). There looks like there is just enough room there, under the bunk, but behind the wheel well. That space under the bunk is empty space in my trailer, originally consumed by the heat outlet, with lots of space on either side of it...the water lines run right through there on the floor, running between the galley up front, and the bathroom to the rear, so it could easily be connected there, and would be much easier to access *when* (not "if") you need access to repair a leak or replace the stuck/worn out check-valve. That is the main issue with the original inlet at the rear corner; the connection inside the trailer is almost impossible to access. On the other hand, it "looks" period-correct. I really don't like the look of those new inlets, (wrong shade of "shiny"; looks out of place), but that one model seems to be the only one in existence. For some reason, it doesn't look so out of place on the late-model 'streams. I dunno...maybe its just me.
As for the electric--a PO installed a telephone inlet plug in the back panel, just above where you have your tape marks, so I was going to take that out, and fill the hole with the 110 inlet. only problem is that this phone inlet is the same dimensions as a standard interior wall plate, which isn't the same profile as the 110v inlet. You know when I take that thing off, there's going to be marks in the clear coat. It would be nice if the electric inlet would cover it over, but I don't know that it will. other option would be an equally ugly hole with a patch over it, so I don't know how I'm going to address that.
I was looking at the prices on these inlets and the cables and such...makes me wonder, why do we need an "inlet"? maybe the hard-wired cable that was there originally wasn't such a bad idea. not so easy to steal, or drive off and forget, either.