"It is funny that Tinder is marketed as a 'hook up' app (at least it used to be) but 90% of the girls on there specify in their profile that they are not interested in hook ups. Or are they just being coy?"
Sounds like a big investment in time. Which might be ok if you're looking to develop a SB or UTR/ATF. But perhaps if ladies posted as a more traditional escort things might develop into something more.
Example: Perky might state that she's available as "arm candy" for special events. "I'll drive the folks at your class reunion crazy!" "Let me be the hostess at your business event." "Add me to pictures of the car your selling and I'll drive customers to you." - You get the idea.
Prior to joining "The Hobby", when I became single, I wanted to learn how to tango. On a "traditional" dating site I found a lady that also wished to do that. We met weekly with nothing else going on. Class, practice and coffee afterward.
HOWEVER, about 7 weeks into our lessons we got a new instructor. She was Hotter than a $2 gun. 3 weeks after she gave me "praise" and asked (privately) about private lessons. From then on we were doing the dance of the sheets.
Eventually the lessons ended and she moved out of town. Also lost my regular dance partner but it was all good.
If you have the time and patience to "get your foot in the door" perhaps you'll eventually get your dick in something else.