I think a trailer with a generator could be quite a good idea. There are a couple of things to look at though, much of which will depend on your own needs.
One is do you really need it. If you need to travel a long distance all the time then a true hybrid would probably be best in the long run. If you only need to travel a long distance once in a blue moon then you might be better just hiring a car for those occasions. If you do weekly short travel but longer on the weekend then a trailer that you can attach/detach as you need it would be perfect. What you don’t want to be doing is carrying around all the extra weight of a generator and fuel when you’re not using it, on the other hand you also don’t want to carry around ½ ton of batteries when you’re running purely on the generator.
The other thing to look at is the generator itself. Cars these days have very strict emission controls, if you’re not careful an old generator could be spewing out a lot of stuff you don’t want.