For what it is worth, there are other options that exist although they may not be as good as the one that you are looking for.
On my last hunt I used a pair of wooden blocks (search the archives here for pics). They are basically triangular pieces of plywood glued together with a slit in them to accept a 1" webbing strap and cam lock, a similar (cheap) lone wolf style strap.
I only used 2 blocks on one strap. The middle step is the top rung of my LW sticks. In other words, I use 3 total steps at my hunting height. One of my feet is always on top of my top LW step, the other foot rests on one of these wooden blocks. Works for me.
Keep in mind that these will not be as tight as a ratchet strap but it appeared to work good enough. The blocks do have the potential to move around slightly, but I try not to jump around and dance on them while I am in a tree. The worst thing that can happen is one will shift enough to cause me to rely more on the LW stick - and I am still tethered to the tree with my lead line in case of a 'fall'.