On Thursday, April 23, 2015 at 8:48:24 AM UTC-5, Bill D wrote:

Doubt that. The wing root is just a handy place to put the battery. There's plenty of room in the other root for an O2 bottle.

And as Jim Payne said while flying a 21 with AF Academy Cadets in strong conditions, "Enough room to hide an extra Cadet per side as well."