Marketing your product into a new niche (alongside your existing ones)

tl;dr how to market to existing Patreon users? Looking for advice. Will provide coffee / lunch / witty repartee.

My product Trolley is a payments platform that makes it really easy to sell online (it gives you a full Stripe integration with a bunch of other features in 5 minutes flat, from any website)

I've realised that the combination of the ability to put Trolley on any website, with my about-to-be-launched Subscription Payments feature, makes Trolley an ideal "lightweight" Patreon (monthly subscription for an amount the user controls)

While I can easily follow all the standard marketing advice for customer research, content creation, competitor analysis and so on, I'm looking for the inside track.

Does anyone here know this market and would be willing to help me out? Would love to jump on a Skype call (or if by some miracle you're in London, or the North of England, coffee!)