I believe that the elimination of the Insignia Blue surround on Gloss Sea Blue painted areas was made at the manufacturer level. I know that Grumman was the first to do this at their primary plant with F6F-5 production. Since the FM-2 and TBM were license built by other companies, they were more likely to follow the painting regulation instead of Grumman's cost saving measure.
Also note that all war-time Corsairs used the Insignia Blue surround as well.
BTW, the skin looks great, Greebo.