That's the good news. The bad news is that they're only allowing 3 hours for prep and cooking-including the marinade. Thanks, Jeff Hi Jeff, It's always nice to hear from a properly respectful devotee. Actually, what you are doing is the best way. Too much wood spoils the meat.
Good charcoal is really sufficient to provide the flavor in most cases.
A handfull of green twigs from oak, hickory, maple, alder will give a boost. I've never cooked with aspen. Why don't you burn some down into charcoal, try it and tell me how it works. I'm certain other suitable species, apple, pecan, etc have been transplanted to the area. Offer to help their owners trim them up.