yeh i rekon i could do all that, but the its injecting that i think would be hardest, especially if oil is thinkI also like rear delts.
The way I do them is I reach my pinning arm as far across my body to the target rear delt as I can. That isn't enough to reach it so I then use the hand of the side that will be pinned to pull the elbow of my pinning arm even closer. This get me all the way there for a smooth shot.
are you using your index finget to inject? or thumb ?