I just measured our NRS frame and it's only 41" between the tubes and the cooler didn't seem to be rubbing too hard on them. The frame isn't touching the tubes at tangent to the circumference, so they are already turn away from the frame at that point. I'd think with 44'' between the tubes you won't have any problems.
As long as it's not loaded GC style and as far as top heavyness goes, most of the weight in the cooler is the block ice in the bottom.......unless you're filling it to the tippy-top with liquid refreshment.
Then you're gonna need 3 people to help you put it on the raft/cat.