Need some suggestions on upgrading batteries for dry camping

Unless you enjoy being trapped in camp all day listening to your generator drone, you want the largest charger your generator will support and enough batteries to accept the max charging current at least during most of the bulk charging. Plan your system to cycle between say 60% and 90% state of charge. You don't really want to run a gen for that last ten percent, get that on shore power or solar.

AGM is your friend if you have the budget.