It might not work out for all the keys. I don't have a poker to check, but looking at the picture, I don't see why not. The keys look to be all in the same positions as a larger keyboard.
I say: cut out the main area (with extra room, just in case) and compare it with the switches. Any ones that don't want to fit, you can just cut off that section of the plate. IT should sit on top of the keycaps pretty easily.
Just make sure you have enough space for the stabilizers, etc. Especially around the spacebar.
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Another option: See if anyone wants to part with their plate they got with their GH poker DIY kit.