You can get bootable partitions in Mac OS 9 via Disk Utility in OS X, just need to make sure to use "OS 9 drivers".
You may perhaps find the ability to format more than 8 partitions if you use the command-line interface equivalent of Disk Utility, "diskutil". You specify the number of partitions you want. Try that?
Maybe worth a try, you can also try using Mac OS 9's
Drive Setup 2.1 (Apple - 2001), or
Silverlining Pro 6.5.9 (LaCie - 2007). That particular version of the LaCie one isn't in the Garden yet, but I plan to address that later this week. I don't know if either will support more than 8 partitions, though, but there is a good chance it might.
LaCie's is in fact the only one that I know to be able to adjust cluster size (!), and I think it also offers RAID 0 as an option (for ambitious MDD owners out there, you can e.g. get 8 256 GB SSDs to create a single, 8x faster, 2 TB partition).
Personally, though, since anything other than Mac OS is junk to me, and also because bloat is a problem, I recently just fully switched to 2 partitions: "System" (OS-bound files) and "Files" (anything "portable", which is almost everything). If Mac OS 9 could boot from bigger-than-190GB partitions, a single partition would be all you need, although it is advantageous to have 2 partitions regardless, due to a few reasons.
Anyway, good luck!