Turn-Key clamps work even better than cable clamps with the Wench, since they are continuously adjustable. Try the search button.
One small point about your post: I didn’t quite say that “tunica” stretching is what causes shaft gains. I believe that the tunica is an important part of the shaft, but it’s not the only structure that matters. It’s also important to stretch the contents of the tunica—i.e., the CCs. I think that jelqing really helps to build the CCs.
Based on what I know, I think stretching up has a lot more promise than stretching down, since upward stretching subjects the entire shaft (inside and out) to tension. That said, very few people report significant gains from upward stretching. Perhaps it’s just that hanging at high angles is harder to do than hanging at low angles, so few guys try it for long. I don’t know.
Plenty of guys claim to have gained from hanging at low angles (targeting the ligs). My personal experience with lig stretching is that it loosened my ligs (and lowered my erection angle) but did not increase the length of my penis.
I’ve had my best results hanging SO with MODERATE weight and combining my hanging regimen with jelqing. Actually, what I do is hang to increase BPFSL, and then jelq after a few weeks of hanging to build CC volume enough so that the EL catches up with FSL. Then I take a break and start again.
My personal experience with downward hanging is that it does lower erection angle. However, this change does not happen overnight. Therefore, I wouldn’t worry that one morning you’ll wake up and your erection will be pointing to the floor. If you decide to hang down, you can always switch to upward angles if it starts to look like your erection angle is flagging.