I am not great at the net, but I am going to try something new. We'll see if this works. I could get a little more detailed if it works. But with the pics, this might also help.
I hope the pics help. I have pics of the other side as well if anybody is interested, although the other side was not as bad. Just had MANY pinholes. So I just bought a kit from POR 15. A floor pan resto kit. Comes with like a fiberglass matting. You paint on the por 15 then lay the matting down, and paint over that. Let everything dry, then used a brushable seam sealer over everything. Then painted again. I wouldn't recomend getting rid of those vents as they are your fresh air vents going to your fan/heater/etc.
Oh, and don't mind the yellow paint on the patch piece, it is off from our parts combine. Hey, at least it is a (ford) New Holland!!
Yep, fender has to come off. But it really is pretty easy. Windshield is still there. Although I just taped and masked it all off when I painted everything.