That should work fine, and at least
it explains why it's acting the way it is. Good thing you didn't try
to fly it that way. You are to be applauded for being cautious,
and observant.
Do you know what vehicle those cores
came from? I know the Chevy Caprice cores from 77-90 do not have
any sort of dividers in the tanks. Here's my favorite
evap core page- http://www.frigidair.net/Parts/product_EV.html
Cheers,
Rusty (can feel my homeowners insurance
rates going up)