Several people should drive by, on the upper deck of 183, in both directions and see if the conditions would allow for drivers to look to the right or left to see the sign or would they be focused on lane changes or something equally distracting.

I never pass the building on the upper deck but I do pay attention some signs on my way like the car wash sign that has real birds sitting in a row(ready to poop on your car?). I also make the Toyota sign a landmark to merge off the highway soon. I just sayin...

Lets make sure we need a sign up there. Maybe we need a directional sign down on the access road.