Not a WSM, but the couple of times I found my self running out of charcoal and needing to re-fuel, I just finished in the oven. We're talking about the last 1 - 2 hours of a 12 hour smoke. No harm there and just easier.
Proudly Smoking on a UDS, PBC &
Accidental Winner of the 2012 "Saucy" Throwdown.