Some advances were made in my indoor lighting setup – I finally got my two external flashes synced properly! The primary problem is that, even with 2 external flashes, the pop-up flash of the Canon 7D will still fire. The popup is way to harsh for close-up shots, and creates undesirable cast shadows. The next step is to use a cable to an external flash, rather than wireless, since using the cable should disable the popup flash. Of course, mounting a flash on the 7D would have the same effect as the cable, but gets unwieldy for handheld shots, especially portraits.