Bum first (Frank) breech is the best presentation for vag birthing a breech Only thing to be a little concerned about is that with your bub being prem, it's likely her head is a little bigger than her hips so that's probably the only thing that might throw a spanner in. I'm sure the drs will be all over it though - I think it's awesome they'll let you give it a go.
IMO, I don't think it's selfish of you to want to try a vag birth. I understand in as much as I possibly can having not been there myself. I wish you all the best - hoping that little girl stays in for a bit longer!