Dan, I've been working with the Booksmart metals as well (Satin Silver). Agree with you on the difficulty and how finicky it is. The only thing that works on my 3800 is the front loading path, of course, but with that, there's about a 1" border on the top and bottom. It also means that the 17" isn't an option since the front loading tray only accepts 16" wide stock. FWIW, I've been using the Epson Premium Lustre profile for soft proofing, adjusting the proof and printing with excellent results. The biggest issue is in the overcoating. No matter how careful you are, dust spots in the overcoat are inevitable. I've even taken a couple to a local automotive paint shop, figuring their paint booth would be a cleaner environment than my house and still there was dust in the clear coat. Wet sanding will take those spots out but then you'll get new ones with the next coat.
I've tried using the DASS Universal Precoat on some Booksmart metal that I messed up the printing on (stripping the ink and Booksmart coating) and while it works, it dries with a whitish hue rather than being clear. Does the Inkaid coating dry clear? If it dries clear, I'd like to try using it on some regular, unpainted aluminum flashing. That combination would be much less expensive than the Booksmart products.
Another option I've tried recently is the Red River Metallic Silver paper. It's an actual paper with a metallic-like coating. Quite shiny but holds fine detail about as well as the Booksmart metal does. Same process of proofing and printing using the Epson Premium Lustre profile works as well. It's pretty reasonably priced too.