Help with Ampeg SVT-2 Pro & Multiple Cabinets impedance

A friend has loaned me an Ampeg SVT-2 Pro to use while my QSC PLX1602 is being repaired. I usually use (2) 8 ohm 1x12's on one side of my QSC and (1) 4 ohm 4x10 on the other side of the amp. So, I have 4 ohm loads on each side.

This Ampeg is cool and sounds great but there is only one speakon connector on the back of the amp. There is also a switch for 2 or 4 ohms.

Can I run: Amp > 4 ohm cab > 8 ohm cab > 8 ohm cab? If so, what's the total impedance of that configuration? Is there a better way to use all 3 cabs with this amp?

Anyone have any other tips about this amp?