I had fairly good luck with charging by booster cables and also a thick charging cable permanently run to inside the SUV storage area. We would drive around charging a second battery while doing errands or sightseeing. Enough that I did not have to idle it to charge all that often. AGM will charge up noticeably faster. Switched the batteries once a day.
This is not too practical with big 6 volt wet cell batteries, and with the low voltage of most vehicles alternators it takes a long time to get much charge in. It worked better for me than most as I also switched in a diode to the alternator sense line, which would boost the voltage by 0.6 volts (may not sound like much, but it better than doubled the charging current)
After a while I decided to put up with some noise and got a generator, it really depends on how many days and how often. Once we got past about 3 weeks of dry camping per season the generator was worth it. I recently got a quieter generator too.
LEDs are an easy and cheap way to save power, esp in the summer they can be a fair fraction of your usage.