Hi gpnt!
Welcome to the Forum.
I fitted my own tandem's stoker compartment with Trek 46cm drops some years ago. The extra width was necessary so the stoker's hands in some positions could clear my bottom when the adjustable stem was all the way forward (I mitered and brazed my own adjustable stem, which hss worked well). I see Trek still offer several variations on that same wide-'bar theme, including this one:
Bontrager Race VR-C 31.8 drop 'bar, available in 46cm:
http://store.trekbikes.com/product/bontrager+race+vr-c+31.8.do?sortby=ourPicksThe link to Trek's handlebar page is here:
http://store.trekbikes.com/category/components/handlebars.do?sortby=ourPicksAlternatively, the same handlebars are offered on the Bontrager page (Bontrager is a brand wholly owned by Trek):
http://bontrager.com/products/components/handlebarsThere are lots of helpful photos on each page, and a wide variety of straight handlebars as well as drops in many widths, including very wide, though selection varies by model.
I ordered a set of Trek's Bontrager compact drops for my Nomad and was pleasantly surprised at how very nicely they were designed and made; very high quality construction, though the lasered brake markers were off side-to-side; I just placed my levers by equal measurement with a tailor's tape. Trek/Bontrager handlebars can be ordered from any Trek dealer, and delivery times are typically 10-14 days, max.
Hope this helps.
Best,
Dan.