Those rackets you listed in the signature line are not what I would call arm friendly.
If you want to go large and wide with the racket, maybe try a volkl v1 oversized as volkl will eat vibrations.
If you are digging the poly but it causes issues, maybe try the hybrid with the soft string in the mains and poly cross at low tensions. Something like a good multi in the mains at 50-55 lbs and a poly cross -5 off the main tension. Ex: mains 52 with cross at 47.
I have been playing poly's for about 10 years now - mostly hybrids. I have been using multi, gut, or syn gut in the mains with poly cross at low tension (poly never ever higher than 52 bls) for the last year or so, and I am liking it. Started with polys in the mid-to-hi 50s and had wrist and elbow pain but much, much better in hi 40s to low 50s.
Another option is try some of the nylon/poly blends like TF duramix. You'll get some of the poly advantages but it plays a little softer.
Also, you can mix gauges - use 17g poly with 16g nylon as 17g poly is usually a bit softer than 16g poly.