Or you can do more than one trace. If default height trace does not find target do same but lower endpoint by 20 units or so.
Thinking of it you could mix idea with mine. Use tall component (same height for every enemy) to find if there is enemy. Then trace down from maximum possible height to some height that all possible enemies should be hit.This way you should find hit location for all your enemy pawns. Add to this some random variation and use that as hit location for visuals.
I have similar system in my prototype of top down shooter, but I am not yet at point where i need different enemy pawns. However i check if mouse trace under cursor hit floor or something above, and i cheat a bit with hit location to make better visuals.