You are doing good work. Your thoughts and methods are right on. EVERYBODY has had those kind of problems and many other problems with thin metal. It is a welding area that is like no other. It is a learned art form. It takes awhile to develop your own methods that work for you. Suggestions and "tips" are guidelines only.
Example: Experienced welders and some well known books say no gap. I-CAR says must have a gap.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn