Today was an awesome exhilarating day that has revived my sense of pride in this project.
I went to a welder whom I will not name. I brought the piece of metal with me I wanted welded in there. They wanted to see the van and the metal for a quote. The guy looks at me blankly and says $500.00. I was flabbergasted, I asked him why. He said he'd have to cover everything so the sparks from the weld didn't damage my paint, he said it'd take him 3 or 4 hours to cover everything. I asked him if he thought I was an idiot and he suggested I take it to a body shop. I was thoroughly annoyed and left, I heard him laughing as I left.
I called up my mechanic and he told me where to go. I show up and a nice fella name Nick (No crap) greeted me and we discussed what I wanted done. After some talking about my project he was was pretty excited and we peeled the plastic off my roof, he looked around for a few minutes and told me he could do it for 100 bucks or so but to just save my money and button everything up to prevent rust.
I asked why and he laid it out for me.
These vans are designed past the specification for roll over requirements, way past them. There are horizontal crumple zones that are designed to give in the event of a crash so the force on the upper truss ribs never exceed, or even come close to their limit in the event of a rollover.
Further more the flat part of my rib is designed to buckle, the part I cut out, and the rectangular part is designed to flex and take the force of the van in the event of a rollover, I still have one left from my oopsie.
Even if I removed the entire rib the crumple area in that zone would give and transfer force to the other ribs in a rollover, and all the ribs are over engineered. Furthermore even if the structure in the back was completely compromised, the structure in the front doesn't rely on the rear for it's roll protection, they're separate.
So I came home, fitted the vent, made a gasket with butyl tape, screwed it in place, and used some self leveling caulk to seal it. I got the wiring for the vent all run too. I can't find my camera so I'll take photos tomorrow.