As long as its sunny, this will help replace "some" of your lost power every day. It could add a day or two before you need a full charge "in town."
I would (in your situation) rotate your batteries. One one the charger and the other in the camper so you don't run them both dead at the same time.
CERTAINLY not optimal use of your batteries, but it is what it is.
Remember to wear eye splash protection and rubber gloves when removing the batteries. A rubber apron will also go a long way to saving your camping clothes from big burn holes. (Don't ask how I found out)
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW