I have discovered I can cheat, and have a regular store bought bun about once every 3 weeks and not have any abdominal issues....you may want to consider that.
PLEASE do not even consider taking this terrible advice! As is well known... even if you have no abdominal issues or any symptoms if you are glutened, you are damaging your small intestine by eating gluten. Eating it accidently is difficult enough... to do it on purpose is insanity.
I use Pamela's bread mix and simply fashion it into buns w/ a spatula. I get 9 rolls from a bread mix. You could absolutely use your bun pan. Lightly toasted, they are awesome.