Curious whether mongers have engaged in fisting a gal. I've had a close call where I got five fingers in but the index finger knuckle wouldn't make it. The gal also said "take it easy" so I stopped. Then we had sex and she was actually quite tight. Very elastic down there. I also had only one time where a gal squirted during FS. How common is squirting?
You could possibly find a pro interested in this, but it is really something that needs to be built up to with a lot of patience and trust. It's probably going to be a challenge to find this without several visits.
Probably easier to find a GF who is willing to try.
From my highly scientific sex studies, I would say that squiring occurs somewhat regularly in 16% of women. There are some techniques you can learn up on to make it more likely. Seems to me the key is for them to feel comfortable. I had a girl one time who said she was a squirter and did I mind. "Hell NO!" I said. 30 min later, and probably a liter of lady juice all over the bed, me, the tile floor. It was too much.