We had a box brake that worked well but with more frequent stops it was just one more chore. Eventually we switched to a build in brake. Out of the way and no setup as it was activated by the wiring harness.
But otherwise my box brake models are dated so can't help.
2009 Holiday Rambler 42' Scepter with ISL 400 Cummins
750 Watts Solar Morningstar MPPT 60 Controller
2014 Grand Cherokee Overland
Bob