Hi I have had 3 surgeries on my right shoulder all of which have been absolutely unsuccessful.
I was taught to use my arm by planting the upper arm on the side and using only the lower section of the arm and I cast out of a kayak. I can cast about 30 ft using that method, and I also use the right reel in method, so I not only reel in from the right I cast from the right. Use a longer rod as well it will help you and you should use a tip flexing rod that will allow for a shorter stroke movement.
I have been very sucseccfull in fly fishing this way and I dont tire that easily after about 4 hours or so then I start to use the other hand some which sucks at casting.