Hi fellow Smurf
I think that if you are patting your son all the way to sleep each night, then yes, you're right, it is becoming a prop and that's why he's waking every few hours or every few sleep cycles. Once he comes out of a sleep cycle he needs you or your wife to recreate the same feeling that he is associating falling asleep with.
So, IIWM, I would start getting him use to falling asleep on his back in the first place. Shh/pat doesn't have to be on the back-you can modify it however it works for you and your little one. I ended up just patting my DD's leg, and then would just rest my hand on her after awhile.
Keep in mind too, that the ultimate goal is for them to learn how to fall asleep on their own, ( without any shh or pat) so you would also want to be patting less and less or stopping sooner and sooner before he falls asleep. As Chicane mentioned, it is a process and there will probably be some crying/fussing but if you stick it out, he will learn sooner rather than later as long as you stay consistent.
You mentioned that he fights it everytime-is there any chance that the shhing or the patting is too stimulating for him? If you think it might, then try experimenting to see if another variation works better.
You can tackle both at the same time (reducing the amount/time of patting and side sleeping) or one at a time.
If you keep him on his side, then I also agree with Ali and the swaddle should go for all the health/safety reasons she mentioned.