Thank you! I did have the corruption problem. In fact, my mccblk0p1 reading (1922972) was closer to my blk1 reading (1966080--still too big) than my blk0 (7862272--suspiciously close to the size of my external card, and quite close to the mccblk1p1). Anyway, I reformatted both cards.

At first, that seemed to work. I got over 50% of the download before it crashed. However, after that it started crashing every 5-10%. I got frustrated and re-flashed the device. I then downloaded the image on my XP desktop and copied it onto the external card via usb (faster, having now waited several hours in all for that download, lol), and this time the installer recognized it and successfully completed the process. Yay! Success!

I don't know what the problem was in the end, but everything works great now. Thanks for your help! And great work, btw!