If your drawing skills are good enough to attract an audience, limiting yourself to TF would greatly diminish your appeal to potential patrons. Drawing fan art etc probably generates the most interest on patreon. If you haven't already, check out the top earners on patreon at
https://graphtreon.com/
You can get an idea of the sorts of work (games, videos, art, etc) that people are willing to pay money for. Sakimichan is probably the best example of an artist doing really well on Patreon
If you insist on servicing a small sub-section of the market, your offering would have to be appealing by providing content that people don't just want to see, but would be prepared to pay for, and being one of the best at providing that content. I can't think of many TF patreons that are earning more than a few hundred a month, but these spring to mind:
https://www.patreon.com/Solone
https://www.patreon.com/arania
In my niche, I can't compete in the commission space at all. I've had a couple of people who still commission me because they like my particular style, but it's not something I actively promote when there are plenty of photomanipulators out there prepared to do requests for free. I only make photomanip as a hobby, so money on the side is a bonus for something I would have done anyway. Having a Patreon would probably remove a bit of the hobby aspect of it as I would have to focus on constant output to keep my patrons happy.