I was playing this setup with pro blend in the 60s then 55lb (played it in the 90s and never changed). Which felt like a board and hitting a rock. Recently trying lower tensions but I've gone too low at 30lbs and moving up. I do like the lower tensions for my arm, sweetspot, power, depth.
Stringing 18x20 with poly on a 95 sq is no fun at all, too many strings, too little space. It also feels very wasteful to string it once, cut it out and try different strings and tension so I'm trying to get a better baseline of the tension and string so I don't waste time and strings. The good about kevlar at 18x20 is one of my rackets can last a year.