Just as a follow-up after owning these RAD extenders and the Wally-world camo cushion for a while now:
This week was the first time I actually rode in one of the RAD seats in my Pioneer. I took the back passenger role for a few hours. I have to say that the RAD extensions were a real joy to ride in! Again, I run 6'1" and about 210 lbs, and I was very comfortable in the seat and enjoyed the ride height. It gives you a great view over the front seat riders, and there's no fatigue.
I have given several passengers the choice between the RAD seats and the Wally-world cushion and every one of them preferred the RADs.
Oh, and they don't pop out if you put them on the proper side.