Having a slow charger for off-grid camping is certainly frustrating. The solution is to have a fast charger :) This lets you keep the gen in the truck and just use it for an hour or two a day (or every other day maybe every three days--depends on your whole situation and set-up), which leaves the rest of the day to go away from the campsite as desired.
The idea in general is to use an inverter off the batteries for your 120v needs, except for battery charging. Then just use the gen and a high amp charger to restore the batteries.
No need to be an unhappy camper.
