I usually use the DaylightGeneral subassembly.
By setting the cut1, cut2 etc parameters, you can create a ditch, and by setting the cut test link you can adjust where it will determine if it is cut or fill.
This way, you will have a ditch until the bottom of your ditch is above your daylight. Or if you want a ditch even in that case, set up your fill1, fill2 etc to create a ditch as well.