I'm an expert because I did it once.
I didn't remove anything except the door panel (and all the stuff you have to take off to remove it).
I suppose I didn't know any better.
It wasn't easy, but I managed to get it in somehow. It took lots of pushing and pulling
and leaving some skin inside those tight places, but it finally went in.
I'm glad you posted the source for the channel. I need some, too.
That seems to be a reasonable price. I paid more for mine on ebay.