I couldn't take it anymore. A bit of sanding, gray primer + the rest of a decade old can of Tamiya flat black, then white primer and resprayed the whole thing with yellow. No more light bleed, but I added so much paint that I need to shave down the rolling shutter door panels to make them fit again.
Two observations: I'm now out of primer again, and ten+ year old paint cans can technically work, but it's more like whipped cream than a precision instrument.
It's bothering me a bit that the cab is a slightly more saturated yellow than the rest, but I'm working hard on talking myself out of repainting that too.