Assist feeding is a no go because they fight me so hard I would injure them if I were to try any harder. They pull back, twist, corkscrew, and push the rat back out of their throat.
That's normal, a snake is just not gonna let you assist him without a fight, if you can't assist alone then you need another set of hands.

Get someone to help you and hold the body while you hold the head and assist.

You can do it