change slope of end condition to stay within ROW

I want the slope of an end condition to change if the tie in point lands outside row.  I have created a do not construct end condition that targets the row (defined by feature definition). I have 2 slopes (4:1 and 3:1) that start at a hinge point and extend a length past the row line. The end of each slope is defined by the slope value and horizontally tied to end of the do not construct component. This drags the tie in points of each slope to the row. 4:1 is set to priority 1 and 3:1 set to priority 2. If the 4:1 does not encounter NG when dragged to match ROW if should fail and default to the 3:1. this works when I test it but when I apply it to my corridor it always just shows the 4:1 which lands outside ROW. 

Looking for idea of what I may be doing wrong and/or suggestions on better ways to do this.

Thanks for your help, Brian