6v batts don't really like being floated, so above is good advice. If you do float them, check their water at least once a month, as they tend lose "water" and it is hard to get the exact float voltage per temp so they won't.
I have a hard time with four 6s getting good balance per pair of 6s where one pair loses water more than the other. Eight 6s can't be easy for that!
If the scenario is to store and leave for four months, then IMO charge each to true full and take all the wires off and let them sit. If the scenario is that you can visit them every two months then charge them up again fully and take all the wire off again. Confirm with hydrometer!!!
Only float them if you can visit at least once a month and top up their water for those that need it--some will and some won't-- because it is impossible to get perfect balance with eight 6s and the perfect float voltage at the temp set for the storage place for every one of those eight batts.
You have several ways to parallel the engine batts with the house batts if floating or just float them alone, or take all the wires off them too.
1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
Photo in Profile
2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas
See Profile for Electronic set-ups for 1. and 2.