Electronic Flasher Relay - LED Compatible.
The Tridon EP36 12V (part 20-1037-0) available at Canadian Tire here is a plug-in replacement for the stock flasher relay and works perfectly with LED lamps all around.
The one thing I have not tested yet and likely won't be able to is because this is a 3-pin flasher and not a 4-pin the stock 'trailer' hookup may not flash with it.
What I'm doing for my trailer wiring is pulling battery power to the right rear quarter where a relay box will be fitted and activated by taps into the stock flasher wiring. This way no matter what the load pulled from the trailer socket things should remain stable on the vehicle wiring. (a singe 4-relay hella box will be left-right-brake-reverse and I'll put in another for the night-lighting) This will also mean that I can use the trailer socket as a power source for up to about 30A draw if needed, useful for work-lamps in camp etc.