It's not all in one post in the thread, and there aren't wiring diagrams, but my SB Cruiser thread discusses various 2WD setups I've used on it over the years, most of which use a single throttle-control-source for both controllers.
(the crazybike2 thread has other discussions of various 2WD implementations I've tried; those wheels are inline with each other rather than parallel so the effect is different, regarding steering effects)
At present for SBC I use a Thun BB torque sensor as primary throttle control via a Cycle Analyst v3 to run both Phaserunners, and customized the PR's throttle input ranges on each one to try to match the response of each motor (they're slightly different) to each other for the same throttle input. There is also a thumb throttle on the CA's input (taht it then sends out to the controllers) for the rare (but increasing as I age) times I can't use the pedals to control or start it from a stop. (usually it's used more like a go-button from complete stops, and once I'm moving then the pedals control everything).
There is also a second cable-operated throttle unit and some relays controled via the left brake handle that use the CA / PR setup to create variable regen braking, that I use as the primary braking source nowadays, since the design and weight distribution of the trike means the rear wheels have much more traction than the front, and thus much greater stopping power before wheelskid starts.
It is also a long delta trike built to carry dogs (St Bernards in my case).
