Hey OP I hope you make it to the pros! I am also playing my best tennis and hope to stay at the 5.0 level. I play at a wide variety of temperature ranges from -3C to 36C (basically the cut offs at which I can find no one to play with outdoors lol) so I've experimented with string type and tension.
I used to play syn gut FB exclusively but I've come to appreciate playing with poly, first round now shaped. I used gut/poly for awhile too. I do suggest a shaped poly on the mains and a smooth poly or shaped poly or solid core syn gut with either kevlar wrap or none, on the crosses. The softer string on the crosses will help modulate the aggressive bite on the shaped poly mains. If you do use non-kevlar wrapped syn gut on the crosses, this will give great feel and power (not like nat gut but towards that direction).
I assume you are at least 1.83cm? You should be able to string full bed poly at 50 lbs to start, a few pounds higher if you use syn gut for crosses. As temps decrease drop tension by a few lbs at a time. The CX 200 Tour 18x20 is a such a solid frame and feels really solid on impact. I went with the 2021 (red) version due to its 62ra softness and feel. But I also have a 64ra version (black/red) that I've played with and that provides easier power.
I made a dunlop player's frame thread. Maybe look for it, but I've chronicled my string set-ups and thoughts there to include Kevin Anderson's Revo 2.0 CX Tour.