I know that big hunks can't pass through but for certain discs, can one
get away with a thicker dough with coconut in it?

http://www.wilton.com/recipes/articl....cfm#chocolate

"Can I add chocolate chips, raisins or other decorative items to the
dough?
Wilton doesn't recommend adding any large solids to our spritz recipes.
Large ingredients won't pass through the design openings in the disks."