Of course, if anyone reading this knows of an existing Trigger-Lock plate that will work for a Valkyrie and a Fats shield then I'll owe ya a beverage!
Update:
I just bought myself a beer. Or a case of the good stuff for this One Neat Trick.

Was poking around online looking at Trigger-Lock side plates when I spied a pair that
might have the right extension and mount-hole spacing to use with my existing Bat Wing Trigger-Lock mount hardware. Taking a chance, I ordered them.
These are Memphis P/N MEK1723 - polished "plates only" - for a Victory Hammer. They also offer a set of plates for this model in black.
A disclaimer: My Tourer has a National Cycle light bar with a set of H-D deep profile spot lamps. They're thicker front-to-back than the originals which came with the bar. The N/C part or a Cobra light bar may prove for different fitment challenges, but here's how things stacked up.
First - to clear the turn-signal mounts on each side of the bar, the lower windshield attachment hardware needs a minor modification. Instead of using the two long (supplied with windshield) castle nuts, sub them for a pair of shorter Nylok nuts. I used chrome ones. The upper mounting bolt hardware is fine as-is.
Second - the Trigger-Lock bushings allow for a little fore-aft adjustment by virtue of a set screw which can be loosened then the windshield (or Bat Wing) can be tipped into the desired position. You may or may not have to adjust things when swapping between the fairing and a windshield.
Lastly - this arrangement isn't "5-second Plug-and-Play". It took me a few minutes to finalize the position of everything and I may have to adjust the mounts yet again when putting the fairing back on. Clearance between the shield and the spot lamp housings is nonexistent. I may look into milling the light bar mounting holes a bit to move the bar further forward.
But it works. The shield bears on the lamp housings ever so slightly and this seems to give a bit more rigidity to things.