Dual PCI-e Cards on Delta 3

I would like to run dual PCI cards (SFP network & USB card, both PCI-4x) on a LattePanda Delta-3.  The first is easy with a M.2 M-Key to 4x PCI adapter but how do I connect a second card?  The LattePanda Alpha seems to have an M-Key and an E-Key both of which can be adapted to PCI, but on the Delta 3, the second M.2 is a B-Key and I cannot find a PCI adapter for this format.  What to do??  TIA