Okay, first 5000 frame-long test encode using FRIMTranscode GUI is done. The result is very nice. I selected VBR, and entered 22000 in the CBR box and 48000 in the VBR box.
Dropped the combined output file into latest tsMuxer, output into BD3D ISO, then mounted ISO in virtual drive and used BDInfo to measure bitrates. Average bitrate for AVC was 12018 kbps and 9962 kbps for MVC. In total that's very close to the 22000 kbps average set in the CBR box. As for max bitrate... I'm not quite sure how to read BDInfo's output. It says 39485 kbps for "Max 1-sec Rate", but that appears to be for AVC only.
That's the MVC on top and AVC underneath: