I like it. I'm thinking I want to do something similar except that I personally see no need for an inverter. I can't think of any benefit I would gain by having a 120vAC output. Keeping everything 12v would simplify things, I think (I would still want some kind of ability to have a 120vAC input for charging though - that could be as simple as a Battery Tender SAE connector though.)
That's what I settled on. I built two identical lifepo4 packs in Apache cases and had barely enough room for the battery itself, an XT60 panel mount for charging, a cig lighter socket, and a panel-mount cigarette female-style USB-C+QC USB thing. Fitting an inverter would have required a much larger box and necessitated something other than passive ventilation. Carrying a tiny inverter in the off chance you need 120v for an air mattress or something was a no brainer in my case, and I have no qualms about plugging it in directly to a cigarette lighter socket for such minor needs.
If you build your box with at least one beefier inlet/outlet (in my case, the XT60 which was intended for mating to a solar charge controller) then you have the option to run a bigger inverter by lopping the end off and rewiring, and catch less flak than running off cig socket.
Also note I didn't even have room for a 6-fuse blue sea box. I just run a single 20 amp fuse on 12 gauge wire. If I had built this a few years ago I probably would have run multiple cigarette sockets, xt60s or andersons, and USB panel mounts, all individually fused. Feels good to not over-engineer something for once and build based on my real world experience and needs.