I'm not an expert but walked RoS last month and a couple of things occur to me.
If you camp near Steall Falls, (great location) do you then haul the tent around all those hills and ridges or leave it there and walk extra 5km after the Ring to go get it? Neither seem appealing.
There are some nice spots either side of the river between lower and upper car parks and no extra mileage or having to haul tent. Location may not be so nice as Falls but a little more practical (assuming you would not have intended to take tent with you).
Hope l didn't miss the point