Lownote, that's why you gotta call the Bay area office in person, and ask for Russ Miller. Not only is he knowledgeable about all things plastic, but he's also a modeler and a member (I'm pretty sure) of the Bay Area Garden Railway Society, one of the finest in the country. Russ has been working with legendary outdoor layout and large-scale structures builder Jack Verducci--on a modelmaking book--so he knows that stuff too. Plus he's fun to just shoot the breeze with. Dang, now we'll probably get him fired for talking too much.
Oh, when you call that TAP office (in San Leandro, I think), make sure you ask for Russ. He can walk you through the whole process.