FINALLY can cross the fabricated bumper off the project list, I figured out quick-detach mudflaps so that whole situation is "turn-key". Until I need to add some angle iron to it somewhere for a synthetic line fairlead for the future rear bumper.
The support bracket the mudflap bolts to is about as minimal as I could make it, so that the flaps aren't super bulky when detached and bouncing around in the bed of the truck.
I welded a 3/8" bolt to the bumper leg, so act as a pin to support the inboard slotted end of the mudflap bracket. I then cut up square tube to make a C-channel that the outboard end of the mudflap can secure into with a clevis pin.
So thru the very open fender well I can super easily see the mudflap bracket slide onto the pin, rotate up a couple inches, and then clevis pin securely. It's turned out to be quicker/smoother/easier than I was even anticipating.