Here's a way, if you have the money for it:

1) get two of these in red, with the double over-under mount, and set them to steady-fire as your taillight, giving a centerline reference point so people can determine whether your turn signal is a left or right signal even if it's dark out: http://www.bullled.com

2) get four of those same lights in amber color, and set them to the 75Hz single-flash pattern. Use the 1Sync wire for the left and right pairs so they flash in sync, and get a rocker switch that can fire the left pair (1 front 1 rear) or the right pair (1 front 1 rear) as desired.

3) for the front, use a powerful headlight to serve as your centerline reference point, so the turn signals have context.

Mount the turn signals far-enough off-center that it doesn't take a lot of work to tell that they're turn signals. I know those are expensive, but they're also weathertight and are definitely bright enough to be highly visible in daytime. If you want legal signalling, you do need front signals too.