Corner base trap- to the ceiling?

If maximum absorption is the goal, it is probably best to reach all the way to the ceiling, but, getting close is probably enough.  You most certainly can overdo any kind of treatment.  I once heard a really nice setup in a very large dedicated room.  But, in an adjacent storage room, there were more than fifty large ASC basstraps stored there.  The person who worked on the setup removed that many excess traps that the owner had installed in the room.  

Given how long are bass frequency waves, the pressure of the soundwave is highest at a boundary because the positive pressure of the wave moving toward the wall meets the positive pressure of the wave reflected back from the wall (the incoming and reflected back portion of the wave is still more or less in phase).  A corner has two such boundaries making it the best place to put devices.  Hence, a corner is the best location for a device trying to attenuate lower frequencies, but, people do tend to expect greater results than they deliver.

But, even quite large diameter traps are not that effective at very low frequencies, so that they don't do much below 60 hz or so.  Still, they do tend to smooth out bass response to some degree.  The ASC tube traps have one side that is designed to reflect and scatter higher frequencies (act as diffusor), and one can thereby orient the traps to either absorb and dissipate higher frequencies or reflect that energy back into the room.  You can experiment to determine which is better for your setup.