DD
I can't help but wonder if the industrial velcro might be a better way to secure the tubes with its ability to flex with the boat? I haven't tried it yet but I intend to. The "rounded" lip at the end of the tube will act as a "stop" as to impede any movement if one of the strips of velcro are placed adjacent to it. (If that were even needed)

I am also intending to velcro my plier case to the side of the boat for ease of use. Remove the pliers during portages (yea, I know it's an extra step). I can't wear them anymore as my knife/bug spray combo has priority on my belt.

So you've been using them for quite a while eh? A lot of you cool cats have this whole trippin thing wired 8-).