Hi Dale,
This task is fairly simple when in fill although as per the example above you have to deal with the fact the end condition will not extend without a surface. I would remove the end condition from the RHS corridor and edit the template drop of this particular range to include the ditch invert and the RHS top of drain (that was removed in the RHS corridor). The ditch would be define by 2 slopes and you could then use a point control for the RHS top of drain to match the corridor edge of the other carriageway.
Hope that helps, Dan