I'd focus on the physical containment first, 1/4" end plates, four rods compressing longitudinally, then 3-sided protection nothing too stout required, or 5 sided if desired, then a cover to protect the wiring, accidental shorting.
Many like clear top so embedded voltage / amps SoC displays can be viewed but protected. Or design to fit in a Pelican-style case.
A 4S BMS will have a wiring diagram, 5 wires to the cells. 2 outermost circuits can also be for bulk, 3 go between cells, to the serial connections, see pic below.
I would not hardwire the BMS, but create a female "balancing port" for those 4 wires, 3.6V charging max, does not need to be more than 4A, JST XH style 20 AWG is good enough.
Thus you can swap out the BMS for a balance board, use a hobby charger to do periodic manual balances instead if you like, use a Cellog to confirm everythings OK or do discharge testing of SoH, etc.
Then a separate Anderson pair of sufficient ampacity say a 3C rate, even if you never go over .3C, using tinned fine stranded UL rated boat wire.
That's for normal cycling bulk use at 13.8V
Some like two of those, so charging bus / HVC can be kept separate from loads bus / LVC.