I looked into doing this on my 36CL for exactly the same reason. The difficulty is getting access to the backside. The upper deck is extensively tabbed and there's virtually no access from below. You could pull the hawse pipe and see if you could fish a backing plate in that way, might be room. You'll probably end up having to grind away some solid fiber reinforced resin in that area. I recently repaired my hawsepipe attachment and there's a bunch of solid resin in the area.
I was going to put them forward of the side hawse pipe. Bulwark is flat and much simpler to deal with vs the transom and it's curvature.
Pull both the inner and outer plates off and take a look inside to see if there's room, it might work just fine. Find a pair of cleats and order the fasteners. If you measure the head size on the "screw" for your existing cleat there's a table on the web that'll tell you what size it is. Order a bronze screw the same size, figure out the length from the stackup of cleat, hull, backing plate and nut all combined and get the next longer screw. Make up the backing plates and have at it. It would probably be a good idea to use thickened epoxy on the side of the backing plate that touches the fiberglass to get it good and solid. The bulwark isn't that thick beyond the original cleat location. Put a stainless sheet on the backside where the nuts go. I never got to the install part so how to secure the nuts is a part I hadn't gotten to but you could use stainless and tack weld it to a thin sheet to hold them all in alignment. I bought another boat and am going to save my cleats for it.
Hey just saw you have a newer boat probably with stainless hardware. Not sure but I suspect stainless screws are also available in the appropriate size. Just make a welded backing plate with .125 thick 304 and your nuts, tack them while installed on your cleat so it all lines up then install. Should work just fine, if you can get it in there!!
Good luck