I doubt that you would have to keep more than a couple of 18650's in a plastic battery case to last you most of the day. I bring a couple of spare batteries with me whenever I leave the house but rarely need either one for my single battery mech. You probably would need to raise your resistance a little to about 0.3 to 0.4 in a single battery mech.
QUESTION: If you don't already have a mech in your collection, what are you going to do post-FDA regulation and your regulated mod's processor dies off? How many backup regulated mods is enough post-FDA regulations? Keep a mech in your collection, and you are FDA-proof. Regardless of its simplicity, the Reo is the perfect mod for the future.
I have a few mech mods, just in case. Since the original MVP came out (2012-13?), I've only broken one regulated mod, and one or two tanks.
The broken mod was because I often neglected to properly secure the mod before conducting significant off-road activities in my HMMWV. It was an IPV D3, which lasted for quite a few field exercises before giving up. I kind of beat the hell out of it, TBH. Since then, I've been a little more careful with devices.
However, when I jumped out of planes on a regular basis, I never jumped with a regulated mod, only mechs with drippers - with the battery removed and a couple wraps of electrical tape around the batteries.
I have a few mechs, about a dozen regulated mods, a bunch of tanks/drippers, and about 10 years of nicotine base in the freezer. I'm not set up for life, but that's fine. I can live without vaping - I'd prefer to continue vaping, but if I have to quit that's fine.
BOOM!