Limited right shoulder External rotation at top of backswing

When I motorcycle my with my wrists at the top of my downswing at best my right elbow stays in the same relative position into transition, at worst it slides back (which helps keep the club head behind hands). I have only about 70° of external rotation in my shoulder compared to parallel to the ground in my backswing (measured by foresight cameras). The club shaft flattens out as it enters delivery position because I gain external rotation, but this seems to limit the amount of wipe. My right arm is more by my side than in front of my body at delivery. This position allows me to keep the club head behinds hands, hands close to body, but limits my forward wipe. Additionally, I have a larger chest from weight lifting, so sneaking my right arm in front of my chest is not usually possible without lifting my arms away from my body quite a bit. I am a 4 to 5 Handicap trying to get to scratch. Are there compensation positions I can try given my limited shoulder flexibility and difficulty getting arms in front of chest, and lacking shoulder flexibility to keep the club head behind hands from this position? I am hoping maybe compensations some women need may apply to mthe golf swing may apply to me