I've got three different Martin Fabrication light mounts - they might work for turnsignals.
25640, 20645 & 15635
The only difference I can tell by eyeballing them is the hardware.
Here is a picture, if one of these is something you can use, let me know or go to ebay and search for martin fabrication.
I'd offer a huge and I mean HUGE in a Donald Trump way, HUGE discount on these to a Wristtwister member.