I'm always surprised when I read questions like this because I have so many gay trans friends who date cis gay men, have steady relationships, have casual sex hookups and so on.
I know gay trans men men who use dating sites, go to sex clubs and bath houses or dark rooms. I know trans men with long term gay cis partners and husbands.
Like in all populations, some gay men are transphobic or just general idiots, and it is best to avoid them.
Others don't want to have a partner who has certain physical characteristics, and that's not transphobic (though the way he communicates it might be transphobic/insensitive). But it's completely ok if someone likes large penises that can ejaculate sperm. They have to fight for being allowed to like penis and some went to prison for it, so I think it's disrespectful to call that want alone transphobic. Rejection is not transphobia.
Sometimes rejection is not even about the junk but rather about social behavior or general insecurity (often on both sides).
But only a certain part of gay men is really strongly into penises. Others are fine with other junk too. Several gay tops have told a friend of mine that ->-bleeped-<-ing a man vaginally is a lot better than ->-bleeped-<-ing him anally, for anatomical reasons.
And many (more than 50% I think) are not into ->-bleeped-<-ing at all, they prefer ->-bleeped-<-s or handjobs.
Others just don't care, and are mainly into the man, not the junk.
We discussed this at a group last year that was attended by many cis gay men, and those who had dated trans men said that the body texture changes so much (smell, taste, skin) that in combination with male looks, they just saw the man and didn't care if he was trans.
All in all I've always found that gay men are the most open to me being trans. Over the years, only about 5 gay men have reacted negatively when I outet myself (out of more than 100), and one friend who dates online got rejected only by 3 men out of 60. And even they were polite.
If you want advise for dating gay men you can check out NotAnotherAiden's websites and Gaytransguys tumblr.
Both websites say that the major point when dating gay men is to be confident and go for what you want because gay men don't woo you like straight men or lesbians do. If you wait for that- you can wait long ;-) Gay men are much easier to date than lesbians or straight men or women once you've got the hang of it.