ESXi 6.7 on R660XS

Is there any way, creative or otherwise to install ESXi 6.7 on a R660XS with PERC12 (H965) front controller and no BOSS riser?

The installation iso for 7.0.3 works fine, however I would prefer to begin with 6.7 on this server as I have some spare capacity in 6.7 licensing that I could use while we develop this server as a DR platform for our enterprise.  We have quite a bit of work to do getting everything put together, stabilized and tested before reporting the DR is in a reliable state to executives and given that could take a little time to work out the kinks I would rather use 6.7 and our existing perpetual licenses so we don't have the time duress of a self-destructing trial license or a wholesale licensing shake-up.

The server was a great find on Dell Outlet so I didn't have the ability to customize it.  It came without a boss riser card, with a Perc12i and an NVMe backplane.  So far it seems that the 6.7U3 Dell Custom iso installer does not recognize the volumes attached to the PERC12 (H965i) controller, but the 7.0.3 installation does and succeeds installing ESXi.  As mentioned, drive backplane is NVMe not compatible with any other drives I have on hand, so I can't slap a couple of spinning disks in there as a boot volume.  No BOSS riser so no BOSS cards (without retrofitting).  I have a couple of SD card mirror setups from older Poweredge servers that we had used for booting ESXi, however I shouldn't be surprised that there is no spot available for that item at all in this motherboard/chassis.  Older Poweredge motherboards had SATA plugs on them, however this one does not.  One thing I haven't tried is booting another server with a PXE volume then booting this server from PXE.  Sounds too complicated and I still couldn't be certain that the PERC12 volumes would even show up in a 6.7 installation.   I have also not tried building a custom 6.7 iso using perc12 drivers.  I have no experience yet with that avenue and I'm not sure it would even work, I know there is an age difference and may very well simply be incompatible for other reasons.

If there is any other option that I haven't thought of, please feel free to throw it out there.  A USB attached HDD for example...

<rant> I really want to avoid being forced to overhaul my entire environment's licensing to incorporate one new server post Broadcom.  Let me finish the DR site design and configuration first then I'll deal with license overhaul the next time I need to renew support.  I would prefer to not over-complicate this project to begin with, not to mention the extreme frustration at Broadcom's totally unnecessary overhaul of the VMWare licensing model to begin with. </rant>

Thanks in advance for any suggestions,