People block the box because getting into the box and beating the light cycle saves them about two minutes. There's simply way too much traffic volume shoved into not one, but two lights. The one thing I could think of doing is to make the ramp two lanes (which means fucking over that body shop, but they deserve it) and allow that right turn lane to bypass the light entirely. The left lane could be allowed to turn right into the outer lane with the light, but the inner lane would be continuous flow. You'd have to merge on the ramp, but that would eliminate any gaps in the flow of traffic on the ramp that the second light cycle causes.

Always expect people to behave in their own self interest. Any system that doesn't account for that will never succeed.