Hi stealth man! Thank you.
Yes, there could be different dynamics being cut vs uncut. You describe exactly the balancing problem of finding the perfect placement of the sleeve, and my suspicion is that being uncut one has to place it lower because one can turtle into the foreskin.
I place the cock ring directly on the penis, behind the glans. Then I put on the spandex sleeve. This keeps the foreskin back under the sleeve and provides additional grip between the penis and spandex sleeve via the cock ring. Then I put on the innerwear using the normal spandex sleeve method. Since this increases penis-spandex-grip I dont have to put the spandex sleeve on so low. Sometimes a quarter of the penis length is enough. When the cockring (under the spandex sleeve) exits outside of the silicone ring i know Im in good position with the foreskin inside the innerwear and the glans and cockring on the outside. Then its usually 1-2 cm of spandex sleeve left to pull through before it comes off which doesnt pull through so much foreskin. I then remove the cock ring.