I have my 55 frame all cleaned up, de-greased, and sanded down. However, I can not get it entirely all the way to bare/clean steel so I thought I would take some Rust treatment from Permatex and hit the rough spots. I thought I would then use some Mar-hyde (Bondo brand?)Rubberized undercoating as a final coat.

Does anyone have any advice for a beginner on this?

My only concern is that I have heard the rubberized undercoating is a bear to remove and I have even read posts from people saying that they feel it actaully increases the rust factor.

Any thoughts?