Sadly, I think that you may be right about the RC Church not performing the wedding ceremony, although they haven't had much to say publicly about trans issues. It will not be a same sex marriage, though, so there should be no harm in asking, as long as you are braced for a disappointing reply. I doubt that you would be excommunicated, and there is some hope for the future, I think, as a trans women has been accepted as a novitiate in Canada:
Will the Catholic Church Accept its First Openly Transgender Nun?I know that inviting your mother could cause unpleasantness but I think that your father could be right. She is your mother and although it may not seem so yet, life is short and and I think that it will be sad, if not inviting her makes the rift even larger and more permanent. It is okay to love people even if they behave badly and I hope that one day, you and she will be reconciled in some way. Perhaps your father could have a special role besides Father of the Bride, i.e. perhaps he could discreetly shadow your mother and distract her if she becomes ornery. If things still go badly, at least you will know that it is not because of anything that you did wrong.
If Tyler is Man of Honor, will he plan the shower? I read somewhere that it is okay to have a co-ed shower.
I hope that you do find female friends of your own age in Denver. I think that you need them, and not just for weddings. If I remember rightly, you did once have a couple but they became envious of the compliments that you got from guys, and hurt you very deeply. I think that most of us thought that it would be okay to drop such friends. Cindy, ever wise, suggested that you take them back if they apologised, and in hindsight I think that she may have been right. It would have been better than having no female friends at all in your home town.
Are there any female colleagues, at the hair salon where you work or worked, who would be happy to act as bridesmaids? Workplaces are traditionally a good place to make friends.
Or, perhaps, your father may know some young policewomen who would be happy to act as security and go undercover as bridesmaids. (I thought that it would be a great movie title but I gather there is already a movie with that name.) Your mother could get a real shock if she gets out of line.