'92 Custom w/ '95 MAF 5.0, 33's, 4.10 LSD
Welding in a new transition would probably be wise, for that purpose. Give the perch the rear side strength above the crossmember instead of below.Ah, only trimming just that little bit will absolutely not make it 30% weaker. It will provide an opportunity for a crack to form though. Unlikely, but possible.
I found the explanation behind the, uh, reversible reverse lights switch. Purple/Orange is power to the switch (12V with key ON), and Pink/Black is switched power out of the switch. Because it's basically just a contact toggle, it doesn't care which side is in and which side is out. The wires in turn come from and go to a designated spot in their connector on the fender liner, so they also don't care which side of the switch the signal is coming from. Makes perfect sense now.
The tail lights get their ground (Black) further back, apparently.
Now I just need to go test those conditions... Knowing it's key switched will make for much easier testing, as I should be able to do it myself with the engine off.