I can't help much with the "smallish" part, but will offer an option. I tired of swapping out
batteries on my single 18650 mod, so went to the Sigelei 100W plus and the battery life is great. So if I am going out for the day, I take the single battery mod with 1 spare battery. Longer outings, and even though it is bigger, I take the Plus knowing it will last and don't have to take extra batteries. And if I am going on a lengthy trip, something I very rarely do, I'll have both with extra batteries and a charger. At least I then have a suitcase to carry everything I'll need.