I have a high school friend/ex-significant other who is a somewhat well known transguy. We had fallen out of touch when I went away to college and grad school. Basically didn't have any interaction outside of Facebook friendship for 7ish years. A few months ago he started a fundraiser for surgery and I reached out to say I would be happy to donate if he still needed it...after I had paid for my own top surgery. I was only out to a few people at this point, and I was super nervous about his response.
He was incredibly supportive, gave me great advice about local resources, and the few times in my transition that I've encountered minor issues or roadblocks, he's happily offered his suggestions. The only person he discussed my transition with before I officially came out was another FTM we grew up with who was also just starting to transition and needed advice.
I know you think coming out to him that way would be awkward, but that is basically what I did and it worked out! I also think it's really helpful to have a real life person nearby who is going through/has done through similar things. Online friends and support is great, but it's nice to be able to physically be in someone's presence and just have them "get it".