Looks good!
I'm in the middle of a similar process doing an aux battery system though it's a little different than most. It's very time consuming to do right (been working on it off and on for the past year or so) and I've been making sure it will last the life of the truck down to each zip tie and stainless steel clamp, lol! Switch has some good tips about the wire loom and zip ties- makes for a much cleaner and durable installation.
If you're finding the cable to be hard to manage, consider welding cable. I plan to put the aux battery in the truck bed, and for the longer run, standard #2 battery cable was okay, but it is a royal pain to work with when it comes time to be connected. I had planned to run most of the standard stuff under the hood between the charge controller, slector switch, fuses, etc, but found welding cable to make this a cinch, and the crimp on lugs do attach better to the additional copper strands.
Keep the photos coming and let us know how it goes!