I’ve been using a 0.5L one for years now. Usually it’s enough, but there are times that when I dry (with toilet paper) I see that I need a little more cleaning and then I either finish with the paper or refill the bottle and try again.

Well, you can spend 300-400 or you can buy a “portable bidet bottle” and clean your asshole with warm water. You’ll still need to use some toilet paper (or maybe a towel) to dry, but you’ll be spending $15 more or less and you can carry it with you when you travel.