It's highly unlikely that the smaller gen. will start your AC unit. It may do it in cool weather if your at roughly sea level. As you gain elevation you will loose HP and thus starting ability with the gen. Every gen. should tell you how much to derate its output based on elevation.
To RELIABLY start your AC you'll need the larger unit.
I would go with one larger gen. instead of two small ones. It would be easier to handle in my opinion than two gas tanks, two things to lift, stow, etc., and the cables to hook them together.