I stole the following from forumdude:
"There is a physical address in Los Angeles, but it's more of a mailing address - there is no actual physical church. However, we're looking into maybe setting one up at some point. We don't post the address on the site but if you order the official documents, the address is on them. We also give it out by special request - if someone needs to put it on a form for their county clerk or whatever."
So I'd order a Letter of Good Standing, since you'd probably need it anyway, and you'll also have the bonus of getting the address as well. Or maybe email center@dudeism.com and wait for an answer.