Last summer I went on a group tour with 16 people, about 350 miles. Other than flats, there were only two mechanical failures, a fairly new external bottom bracket failed and a front derailleur that was several years old had a spring break.

I suggest square taper, pick the brand you wish. Almost every one of my bikes has a square taper including the one I finished building up a couple months ago. (Exceptions are two of three bikes that are over 40 years old are not square taper.)

I do not have a lot of experience with self extracting bolts for square taper, but a friend of mine that works at a bike shop swears by them and has them on all of his square taper bikes. That could reduce the amount of tool weight you need to carry.

You mention you want to switch from a triple to a double, but I (along with others, above) suggest you keep the option of a 74mm BCD granny gear. That means you could get a triple crank but only set it up as a double, then if the need arises you could add a 24t (or other size) granny gear if needed.