I think my best bet would be weatherproof box on the left rear of the roof then down thru the closed that's across the back of the coach. I'f I'm facing the back wall from the bedroom The washer/dryer is on te bottom right corner and the TV is just above.
Note that the battery bank, all 4 6 volt batteries, as well as the converter is on te left rear corner of the coach. So, from the roof's left rear corner down thru the roof into the corner of the closet, to the controller then BIG wires down to the battery bank.
Show us some picture, or a a trailer floor plan with proposed locations of controller and battery. People don't read long text descriptions. You CAN get away without a rooftop junction box, if you run MC4 AWG 8 extension to some closet and install the J-box there inside, not far from its planned rooftop location.
I think I would have no more that 10 feet between the controller and batteries so I should use the larges guage possible correct?
Why "largest possible"? Gauge 6 already gives a pretty moderate 2.3% drop at 10ft. Make it gauge 4 and call it a day. Alright, those from Texas can have it gauge 2, I've heard everything is bigger out there :). Controller allows gauge 2, and I don't think you need it thicker.
I'm wondering if I should mount the controller on bedroom wall just outside the closet. Not sure how much heat could build up if I had the closet doors closed during a hot sunny day.
Hard to tell. If it's not too big closet and filled with other things, I would say - install it outside. Preferably, away from your bed. In daytime the controller would click sometimes, or hum, disturbing your afternoon siesta nap, and Morningstar have those stupid blinking LED lights on controller. Tristar monitor is pretty bright too, I've been told. You don't keep a lot of blinking and clicking toys in your home bedroom, I guess.
I see the Morningstar has an ethernet port for monitoring. I could tie into my internal network & use ethernet for monitoring.
Yes, you can use either a remote display or a laptop in lieu of display.