Single speaker dash, speaker depth provisions

[FSHTAIL]

 so I'm ditching the 4x10 speaker in the dash for an 4x10 adapter plate meant for 3.5 inch speakers, I have hugged out the adapter for 4in speakers because I found higher quality speakers for almost half of cheapo 3.5's I looked at.   

In these pictures, how necessary are these sections of metal for integrity? (circled)
I'd like to clearance this metal to clear the magnets on the back of the 4" speakers. 

I felt my hand under there and it didn't seem like there was anything in the way underneath.

Just looking to see if anybody has done anything like this?

I've done this on several b-body cars with zero issue and assumed the same here.         

I just didn't want to put speakers in the door panels because they would look awkward and out-of-place, also the kick panel speaker housings I've seen for 5 and 1/4 speakers seemed really flimsy and a poorly built

[Mr Lee]

Yes, I just cut my dash frame up too for some speaker enclosures I built out of PVC pipe.    I think there's plenty of dash structure left and once the speaker grille's in place it wont be noticeable. Remember there's another metal frame inside the foam dash pad and that gets bolted to the dash frame structure so that has some strength too. I think you're good to go. 

[HEMICUDA]

You're good, cut away.