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I'm 5'2", and not young. I did have problems getting my "victim" out of the water, but I did well enough to get her to where CPR could have been done. I don't think any of us could singlehandedly get another diver out of the water and onto a boat.
I would certainly not recommend avoiding the Rescue class because you are afraid you might not be able to do that part of it. The class is an excellent one, and you will learn a ton in it, if it is well-taught.
We had my brother (who is my regular dive buddy and a Dive Master) as well as another instructor absolutely show no mercy in thrashing around during panic diver exercises, doing underwater rescue simulations, and full-on rescue scenarios. They really put me into stressful and very realistic situations in sometimes less than ideal water conditions (choppy seas, currents, surface swells, etc.)
I was told by a staff member that the course was very rigorous physically. My experience (at then age 52 and in "good shape") was that it was far more taxing mentally than physically. Plus there is a lot to digest in that manual. I have read on SB that the degree of physical and mental requirements varies quite a bit according to instructor. It may be best to ask the instructor/shop what will happen in the course. Of course the tougher the course is, the better you will turn out. However I have also read of odd occasions when an instructor will go way overboard or do some strange stuff.
I've launched and recovered many thousands of divers in conditions ranging from flat calm to 12 foot seas in a 10 second period. Never once have i seen a diver splash at the surface like they do in a rescue class.