I was thinking about your idea to outboard those ford mounts. I have been planning to do that little mod to my FRONT mounts.
I would have to do some measurements but my feeling for the rears would be that they would rub the inside of your tire when flexing. At least for my set up it would. I guess it would depend on how wide your axles are, the offset of your rims, and if you have some spacers. I have Dana 44's out of a Wagoneer that are about 59" wide, and I believe if there were shock posts sticking out into my rear fender wells they would rub against them with even the slightest articulation.
I may again be mis-interpreting your plan. However, more proof of not having enough room to put any mounts "outboard" of the frame in the rear is that the stock mounts are inside and completely out of the way. I think it is that way for a reason.
I guess maybe try and put the ford mounts in place before taking the rear tire off and seeing if there is enough room.
When I get a ton of flex in the rear I am insanely close to rubbing the inside of the rear fender wells. If there was anything in between the inside of my tires and the wheel well it would rub.
Whenever something breaks on my Cj... I learn something new by fixing it.