What's helped me tremendously with any of these devilish rubber trim pieces is using cable pulling lubricant. It is an entirely different level from using silicone lube or soap and water. It's a little more expensive but totally worth it.
I think this is what I have out in the garage:
https://www.grainger.com/product/10F523?gucid=N:N:PS:Paid:GGL:CSM-2295:4P7A1P:20501231&gclid=CjwKCAjwzo2mBhAUEiwAf7wjkhujK4-NvoRds6Ni2Tgm_e1E24RR5rXduFqEV5raqsEtB0PYMy-aNxoC2lYQAvD_BwE&gclsrc=aw.ds
It's designed for pulling heavy cables jacketed in rubber that are hundreds of meters long. It just works.