I have one of these LCD finders on the way thanks to a nice deal from an upstanding forum member:
I checked my arca-swiss plates, and I do have a smaller one that has a 1/4" female thread in the bottom. I will try that one first to see how it works, then take it from there for any other modifications I might need.
I decided that although I don't need this now since most of my shooting has been inside looking out because it is winter, once I get outside in the spring this will be a big plus when shooting in the sunlight.
Also since it is easily removed, I can possibly see a use on my K-5 also.