Okay, here's an update:
Took the big one back to Lowes, and went to Petsmart and bought this:
Simple Solution Spot Spotter - Dog - Sale Category - PetSmart
I was doubtful about its performance, as I had read some pretty awful reviews for it on Amazon. But I figured I'd give it a shot.
My black cat finally exacted his revenge on my being gone for a week by peeing in my, all things, gig bag! He mostly peed on my Sure microphone box (maybe trying to give an opinion? thankfully the mic wasn't in it!) and of course, on other stuff as well. I brought my (very stinky) bag in the bathroom, which has no windows and is pitch black with the door shut, and turned on the light.
HELLO! THIS THING WORKS! You have to get it pretty close to the area, but it lit it up nicely. You could see exactly where the urine was and wasn't. I guess this thing gives off the right spectrum wavelength?
Hopefully, I can salvage my gig bag. It's actually just a travel suitcase that I got for my 10 year award from work. I bought a big bottle of Nature's Miracle "Urine Killer" for it.
Will update later on the de-stinkification!