Ok so you set up at first with your batt on the tongue and some more batts on the ground in parallel. After a while you have them all down to morning voltage of 12.2 so now you need to do some sort of recharge.
Take all except the one out for a recharge however you do that and get back. Now connect back up and use them some more--the not recharged one will equalize with the others over night, coming up more than they each come down, but you are back in business.
Don't worry about all the bad things you should not do with batteries 24/7. Just get the camping done and have a good time. You can sort out the batteries with "recovery " sessions when you get home. No big deal.
It is the camping time that counts. Batteries work for you; you don't work for them.
