Clack

After much gnashing of teeth, buying additional hardware, wailing, and utlimately pleading with the Computer Gods (Praise Be Unto Linus, He of the Free Software) I figured out what is happening.  This update is for anyone else running into this issue going into the future.
 
Dell BIOS, as best as I can tell, has an incomplete or buggy Legacy Boot option and needs a UEFI Boot to properly identify all the devices on the SAS9200-8e HBA.  Poster Mthrboard over on Serverbuilds.net posted an excellent how-to guide on updating the LSI HBAs with a UEFI-capable BIOS for boot, and following it to the letter updated my board firmware, BIOS, and most importantly from what I can tell, the UEFI ROM loaded on the 9200-8e.  The firmware, ROMs and appropriate sas2flash EFI versions are present in their links, and following the update procedures there allowed me to boot with the HBA via UEFI.  I booted into the Windows instance I temporarily installed and found that every drive is present and running fine, and from there Unraid recognized all the drives and I have my 30-day trial running successfully.
 
Special thanks again to Mthrboard over at Serverbuilds.net for posting up that how-to that basically solved every issue I've had with this Dell Optiplex-based server build.  I also happen to have an extra forward breakout SAS-to-SATA cable as well as a pre-flashed SAS9207-8E to put up on eBay real cheap sometime soon.