I hope you come back from Steemfest and can educate us all about this! I'm far from being an expert, but I think SMTs brings Steemit closer to the Ethereum model, which propelled it financially, but also had significant flaws.
There's a lot of great urbex stuff on YouTube (same with climbing and bouldering, which is my passion). I think one way to attract other urbexers to Steemit is to point out that they could make small amounts of cash via Dtube. YouTube rewards have plummeted recently. And Dtube now allows people to upload their old videos to the platform - I think they get paid in DTC rather than Steem for this. If that worked, that would be one way of building up your tribe, and then you could add the SMT as it grows.
Have you tried Instagram? I've dipped into it, but I've just never got organised enough to use it regularly. But I do notice that it's a brilliant way to pick up followers for your niche. Just post photos and add the relevant hashtags (and of course a link to your post). I think it would be a great way to get outside attention for your Steemit urbex blog posts. That dilapidated adventure park shot would definitely attract attention.