Are you aware of Kneesavers? These are a short male-female extension that moves the pedals outward a bit.
Available from many sources, but here is one with a pic-
http://www.thethirdhand.com/Products/SC-PDA.html

Do note: using Kneesavers may require you to change the pedals and/or the cranks.
Some pedals only can be tightened with an Allen wrench (through the crank end hole) because they have no flats, and there's no way to tighten such pedals into the Kneesavers.
The other issue is that some super-light cranks have broken when used with kneesavers.