I'm headed out of town Thursday for the weekend plus a few days, so I ordered the plate; it should be waiting when I return:

It was $73, because I had them tap 16 holes. Without tapping it'd be a third of that price! Wild. But I love a machined and tapped aluminum plate, it makes assembly so pleasant. Lots of locating nubs, too! The top one is from the tensioner bracket; I added this part and a knob, and made a few other minor tweaks before sending this bit out for fab:

I also ordered some hardware that I didn't have in my cheap-o assortments: 40 mm M3 and 45 mm M4 socket head cap screws. Also a few parts for another project.

Excitement!!