If you contact Charlie Green @ G&D Trikes, he has a diode set up that allows you to turn the 'Whale tail' spoiler into a running/brake light.
I know on the brake light modulators it tells you how much the unit can handle or how many brake lights. I believe the one I installed on a client's trike would only handle four. I don't recall the brand off hand, I'd have to check records and report back. The unit is a 'Back Off XP' and it is used on the GL-1800. It's easy to install and you get two different flash modes with it.