I'm going on a camping trip and I reeeally want to bring my bass to play music with people.

The problem with electric bass is it sounds crap with out an amp (if you can hear it at all in the first place), so I'm trying to find some way to play bass at a camp and be audible.

Portable guitar amps are too small and will either break or just be too quiet to hear if used for bass.

I found one guitar amp that could work with bass and could be be charged from the mains. But you only got 1 hour of play time per charge. This wasn't worth the £50 it cost.

Is my only alternative buying an acoustic bass?
I wouldn't bother taking it, tbh. Basses are large, heavy, and awkward things to have in a tent. And you don't want to leave them where it might rain.

Unless the camping trip's a week long, you should be able to do other stuff. Take an acoustic guitar or something if playing music's that essential to you.

As far as portable amps go, I think you can get a Roland Microcube for the bass:


But it's not cheap.
Another option is the Pignose H30 amp for keyboards/bass. I've used it for small coffeehouse like settings with acoustic guitars and its workable. However, like other battery powered amps, the battery only runs 6 - 8 hours without a recharge, which if you are roughing it in a tent may not be practical.
Buying an acoustic bass isn't a viable option either, unless you're willing to shell out for a Tacoma Thunderchief. Problem with AB's is that they do not resonate as well as acoustic guitars do, so they will still be drowned out by someone playing an acoustic guitar.

I have an acoustic bass myself, and it's not the loudest thing in the world. You could go for it, but I wouldn't buy it specifically for the trip, as you could use that money somewhere down the line for some new gear.