The setup is perfect for me. I did do additional takes on the track and used a de-esser and a second noise gate to squash most of the squeaks but I couldn't eliminate it completely. On the slide parts, I played them using more of the lower finger instead of just the fingertips, which helped some. It's just a demo mix for myself but it is frustrating when I only have the issue on bass but not on the guitars.
Bigger wound on the bass strings. Try some hand cream...no joke