I also had that issue about skin.
You could try to place your thumb right above your shaft (press and hold but not very hard, just hard enough to keep the blood in).
From my experience, this has not only helped me get and maintain an erection during jelqing, but has also reduced the skin problem while jelqing.
This little trick has been mentioned by someone here on the forum, I forgot his name, but I’m thankful to that person because it has helped me a lot!
At first it was a bit weird to jelq only using one hand and keeping the other hand on my leg, while my thumb was pressing right above my shaft.
But I got used to it, and now I would find it weird to jelq with both hands again. I’m not going to use both hands anyways, or else I jelq some skin too and have lower EQ.