I read your post About the issue of hyperblinking after switching to LED lighting.
I experienced the same thing with my 2008 F150.
I went to my Ford dealer and they explained it was because of the lower voltage draw of LEDs Just like you stated; it’s a feature to warn drivers about an outage.
I knew about the the fix you proposed but the Ford dealer gave me a much better option, just change out the standard flasher with one rated for LED . No removing tail lights, or splicing wires etc.
It’s worked great for years now. About $15.
Pass this on. Oreillys sells the same stuff.
It’s much easier than splicing wires, which we all know contributes to electrical failure eventually.