I ran fairly heavy gauge into my doors and I didn't mess up the big molex (can't remember what gauge). I'll try and get better pics. Last pic will give you an idea of the size of wire going into the doors coming from the amp on the left. Driver's side door shown.
Unsure about the brand you listed, but every spade terminal I've ever used you just slide the wire in and crimp...the insulated sleeve that is part of the terminal is meant to be crimped. I don't know if that will help you or not...sorry if not.
As I've been saying for a couple years, no one, and I mean no one, can @HextallS550 for this upgrade. I have documented here many times what great service he's given me; and others have experienced the same.
For the life of me, I truly cannot comprehend why anyone would go with someone else for...
He's in the middle of building a new site. As @thecloneranger suggested, send him a PM and he will go through exactly what you want to accomplish. He helped me in pretty much my entire audio setup (see sig).