Perfection is the enemy of good enough. Per your sketch you have a fairly modest power requirement, easily met by two batteries. The elephant in the room is probably the fridge, not because it draws a lot of power but 12V cooler type fridges usually are on full time. Measuring that current draw with the unit you have or plan on using will give you an idea how long you can go between charges. Or, since it's the fall, you may not need to run it full time which ends up being in your favor. Depending on your actual draws you may be able to get away with just one battery, might be worth looking into to reduce cost, weight and complexity.
Some items I would add are some outside LED area lights, and an inexpensive battery monitor. I see you have a DVD player and a TV which is fine, but when I camp I tend to use an AM/FM radio more than the TV. Draws less power and you can listen to it while doing other things. An old car radio you get at a fleamarket or yard sale is cheap and sounds great.
I wouldn't go nuts trying to come up with a "final" wiring plan and go through any extraordinary measures for an installation right out of the chute. I like the idea of hooking stuff up with temporary runs and trying it out for a while. Maybe even a driveway campout to see what you'd like to have over what you've anticipated. Once you're confident you have the "stuff" you want, that's when you take the pains of mounting them neatly/securely and route your wiring with proper protection and terminations. Start with a functional block diagram with a bit more detail than your sketch has, identifying the devices and their interconnections, and edit that as you go for what you change. That then that becomes the draft for creating the detailed schematic you ultimately end up with for the final unit. I recommend this path not just because I'm a design engineer and do assembly diagrams and schematics for a living but because if you don't, you will never remember what you did or what you have and updating it and maintaining it going forward will be a giant PITA. Any and all documentation you do now, from framing to plumbing to electrical will only benefit you going forward. Even just photos you take with your phone showing how something was put together along with the packaging showing some part numbers for stuff you bought is great information. A three ring binder you keep all your scribbles, photos, receipts and any data/instruction sheets that come with purchased parts becomes your owner's manual, something you will always want to have.
Mark B.
Albuquerque, NM