Hmm I m not aware that I have to balance them regularly , I think BMS does that and I can do it very 6 months (the boat sails 6months per year) with the victron charger , or not?
In all the previous banks I ve installed I screw down to the floor the batteries with some distance between them . As I am planning to do now but with an extra frame around them . My guess is since they are fixed the bar is not gonna stress them , since there aren’t any forces applied to the bar except the cables elasticity coming from loads/charges. Is true that if the bar was the only element keeping them fixed it could be a problem. Maybe are you talking for some other stress force like vibration?