I'm a bit late on this thread, but aero bars can help a lot by providing a better position. I am putting these new
NItto Bosco Bars on my touring bike. I've used them for a light touring hybrid this summer and have not experienced any numbness at any time, even during a century ride.
They look like an old-fashioned cruiser bar, but they aren't. They provide a huge range of body and hand positions including a very nice aero tuck when extending to the center of the bar. Check them out on Rivendell's site.
Marc