I was thinking about adding one of these but i saw a better way to mount the tripod. The two front legs were extended out to behind the seats, and the third just extended out to the back, and they used a tie down like you did but i think it was from around the rear speaker area to the other side. If i can find the picture ill post it.
Im in the same boat as you though, if i can make something work for much less, then im all for it.
