Using a straight cable without switches is a good idea, that's one less thing to worry about. I think I read earlier that you are trying to get 125W Ku. That's a rather difficult one. While it's definitely possible to receive it well, it's also a rather touchy one, a bit like either you lock on it, or you go in circle for a while in the dark, especially from our area in the NorthEast.
Instead, try CGTN on 95W, that's probably the easiest target in Ku. Other fairly easy ones: NHK on 103W and KBS on 123W (might be easy to aim for that one and still be able to reach the LNBF from a step ladder). Once you get satisfactory reception on those, look for 125W.
As far as skew, while i'm not familiar with the SL1-PLL, I would guess that the F connector should be pointing toward the ground when the dish is aiming at the top of the arc, parallel to the polar axis of the mount. and the LNBF should be aligned with the C-Band one in the plane that is perpendicular to the polar axis. Have the front of the LNBF more or less aligned with the front of the C-Band LNBF. Keep in mind that the reflector acts as a mirror, so if your Ku LNBF is East of the C-Band, your aim will be West of the C-Band, so for a given sat, for Ku aim further East to compensate for that difference. On mine, the difference is somewhere near 8 degrees. So for 95W Ku, aim your positionner either to 103W or 87W, do a blind scan, move a bit east or west, scan again, etc. In the end you should find something. Fine tune it as mush as you can
One more thing. Your dish mount alignment was tuned with C-Band. Ku is a lot less forgiving. So you might find that the alignment that was working well for C-Band might not work so well for Ku. You might need to compromise a bit somewhere.
Instead, try CGTN on 95W, that's probably the easiest target in Ku. Other fairly easy ones: NHK on 103W and KBS on 123W (might be easy to aim for that one and still be able to reach the LNBF from a step ladder). Once you get satisfactory reception on those, look for 125W.
As far as skew, while i'm not familiar with the SL1-PLL, I would guess that the F connector should be pointing toward the ground when the dish is aiming at the top of the arc, parallel to the polar axis of the mount. and the LNBF should be aligned with the C-Band one in the plane that is perpendicular to the polar axis. Have the front of the LNBF more or less aligned with the front of the C-Band LNBF. Keep in mind that the reflector acts as a mirror, so if your Ku LNBF is East of the C-Band, your aim will be West of the C-Band, so for a given sat, for Ku aim further East to compensate for that difference. On mine, the difference is somewhere near 8 degrees. So for 95W Ku, aim your positionner either to 103W or 87W, do a blind scan, move a bit east or west, scan again, etc. In the end you should find something. Fine tune it as mush as you can
One more thing. Your dish mount alignment was tuned with C-Band. Ku is a lot less forgiving. So you might find that the alignment that was working well for C-Band might not work so well for Ku. You might need to compromise a bit somewhere.