I went hiking in the Fish River canyon "just" upstream from where your river boating excursion took place.
5 days, 90km and zero facilities. Pristine nature despite it being very popular. Same story as yours: non negotiable items in your already overweight pack is a shovel, TP and a lighter/matches. You had to burn the TP and bury your logs.
Only difference is in the canyon you cant really get far away from the river.
I rather enjoyed the burning ritual afterwards. Somehow it felt like it cleansed my soul, after slogging 25km over round loose stones and soft sand carrying 20kg on my back. It was the little things that made that experience beautiful.