Oval Concepts under only bars work nicely. They are exceptionally easy to get off. (loosen one bolt on each extension). They allow you to get the pads low, helping with the problem of handlebars that are at the right height for road racing end up putting the pads to high for a TT setup. And you can use any handlebar because the bolt into the stem not the bar.
However, they're rather pricey, and you have to use an oval concepts stem.
http://www.glorycycles.com/ovcoa9unonsc.html