Revit :: Show Individual Stud Kicker Down A Corridor?

I need to show an individual stud kicker down a corridor. The kicker needs to kick at a 45 degree angle from the front of a soffit to the wall. The width of the soffit is variable. The kicker length needs to chang and get longer along a 45 dgree angle.
 
I want to be able to 1) set the soffit width or 2) set the soffit width with a type parameter.
 
I have a reference locked to the back side of the kicker. Attached a parameter dimension
 
When you grip that reference line to the back it will extend the kicker along the plane the way I want. However, when I go to insert the kicker, and I change the dimension in the properties window, nothing happens. It just is inserted in the size I created.
 
That's ok. So I was going to create 1'-0" increment sized kickers. Assigning a soffit depth for each one. However than it gives me a constraint error.