How necessary is a taper when ......

You need to consider how long it takes for your body to recovery and adapt to reap the benefits of a long, hard training session.  I don't know if there is any solid scientific data on this topic, but I've read here and there something like 10-ish days.  Perhaps someone can pipe in with some research on this?  You may feel like you've recovered in a shorter time, but if your body has not had time to make the physical adaptations you are looking for to reap the benefits from that training, it's not going to help you on race day.

I think I'd limit things to a last key long workout at least 10 days out, unless the race itself is low priority.

Ah, come on.  Just read your own sig line.  :-)

Insufficient training has never stopped me before...it just slows me down ;-)

Since its a half.  I think you can do a couple of race simulation bricks.

If you will be two weeks out this weekend.  I would ride long on Sat (50ish), run long on sunday (10 miles or so).   Then two bricks at pace, one on Tuesday and one on say Thursday.  Ride 30ish/Run 6ish  both days.   Swim in between.  Then take a one week taper. 

So there, 4 key workouts in the next 7 days.