I have a portable 2 KVA Yamaha generator but rarely use it. The battery is silent, the generator is not, and then, as you say, additional fuel is required. It's a good option in some cases but with all the sun down here the auxiliary battery plus solar works well.
With the 2x 80 Ah batteries on my camper trailer I don't ever run out. I have two 120w solar panels and plug one to the car auxiliary and one to the trailer system. Power isn't the limiter out in the wilderness here, it's water. My camper has 130L capacity so working on 10L/day (for two) I have 10 days. That's just water for consumption. So yeah, it's much less in reality so camping near water is essential usually, although I always bring an extra 40L in jerry's.