I checked all my references and could not find anything that indicated if the deck was painted. One photo I have looks like it might not be, but there isn't enough evidence to know for sure. Anything above deck including the mounts for the torpedo tubes was painted with this scheme. One photo of the 170 boat shows a number on the port cockpit where you would expect it. But I'm not sure if it is really there, is a temp sign they put up, or was put on the photo. There doesn't seem to be a number on the rear gun mount.
You may want to try contacting PT Boats Inc. to see if they have any literature on this. Frankly it looks like a nightmare to me!
Best of luck with your project.
Dave
PS. These paint schemes were only found in the Mediterranean. The Higgins boats that had similar schemes did not have a painted deck.