You're right. I went flipping through the few books I have. I found an artist's rendition of 3-way plans for a D-5 model, and it had no indication of a trim tab on the right wing. I wasn't entirely sure so I pulled out another book. It had a photo of a P47D with oil all over it after a forced landing, the right wing toward the camera. The angle was dead-on for the aileron, and I couldn't tell. Then I pulled out a different book and saw the famous photo of the P47 shot to chit, landed tail-up with one wing shot to ribbons. The other wing's aileron is visible, and no trim tab lines (as on the opposite wing) just the extended tab.
Wish I'd known about this when doing my other 3 P47 skins. It's too minor a point to go back and resubmit them, but I'll keep it in mind for all future skins.