Yea i had that grittie worthless insulation crap sprayed inside my doors too.
Just a fyi, if you can get away with it try and just replace patches on the outer skin and treat the folds with a rust mort of some kind that is liquid and seaps into cracks ect.
I cut about 2" below the body line and took my lower skin off, what i didn't know is that the door skin has a contour front to back and sticks out about 3/8"further in the middle than the ends, when i cut it off the door skin the built in stress relieved inward and whamo no more contour front to back, it went straight across. Welding a replacement skin on and even being super carful to not let it get hot it still wants to go further inward so i cut and removed that skin and started a second time. I followed the advice of another forum member and bought a length of 3/4" angle which was lighter duty than i wanted, i shrunk one edge to put a contour into it, clamped into place and then drilled 1/8" holes, then i took the angle off and drilled the skin up to 1/4" and reclamped the angle then spot welded the angle in place, then i spot welded the skin in place, it still shrunk inward enough that i want to start over again and plan to soon. The point of this is that replacing the lower skin is a pain in the A** so avoid it at all cost..
