Might also want to post a swgoh.gg profile so people can offer some advice on your roster.
Usually people that rail against GA and all of the inherent unfairness in GP related match ups have lower arena ranks, which generally (not always) correlates well with inferior mods (team comps being equal, of course).
As you're well aware, being in a guild that is not full means you're not raiding as frequently as your competition, which will limit the rate you can acquire Han and GK, though I'm assuming that you already have those characters unlocked at 3.5M GP.
Have you considered a merger, or does your need to have your own guild supersede your leadership responsibilities to your guild mates to get them to progress as far and as fast as possible?