Remember what happened to my coil towers in JV, Ryan? if you're ramming into the bumps they are going to start to give up and do the same thing, it's going to take more than just welding a plate onto the outside. Vetteboy redid his upper coil buckets with plate and even he said after awhile they started caving in again. the big advantage to going through to the inside is you can weld tube to the cans where they come through to help brace them from the back. It will work, but not as good as it could. once that upper coil bucket starts caving in it hurts the structure of that whole front corner, even if you bend it back the metal is already going to be fatigued and it will just happen again.
Are you saying the AC and ABS units would have to be removed permanently, or just moved out of the way to do the work? if it isn't permanent don't take the lazy way out, you've done too much good work on that thing to start skimping now.