T_Hastings

I'd suggest buying a cheap pci-e x1 sata controller card, that should give you 2 extra sata ports. 
 
Alternatively, if the ITX motherboard has a m.2 connector, you can buy m.2 cards that convert it to a pci-e x1 riser cable ... to plug a pci-e x1 card (a sata controller for example)
 
example card : https://www.ebay.com/itm/NGFF-M2-to-PCI-e-4x-Slot-Riser-Card-M-Key-M-2-Port-to-PCI-Express-Adapter/274485786798?
or  https://www.ebay.com/itm/NGFF-M2-to-PCI-e-4X-1X-Slot-Riser-Card-M-Key-SSD-Port-to-PCIE-Adapter-for-Mining/254730098594
 
The power cable is needed to insert 12v into the pci-e slot, because the m.2 connector only gives 3.3v 
You can get riser cables to position the sata controller card somewhere more convenient inside the case : https://www.ebay.com/itm/PCI-E-1X-4X-8X-16X-PCI-Professional-Riser-Card-Ribbon-Extender-Flexible-Cable/183283708713
 
example of cheap and small sata controller cards, from 2 to 8 sata ports (18 australian dollars to $49 ausd) : https://www.ebay.com/itm/PCIe-to-SATA3-0-4Port-6Port-8Port-SATA-III-Expansion-Controller-Adapter-Card-6GB/163895437034
 
You can put it on a thick carboard or plastic backing so it won't short and hide it somewhere in the case, if there's no room on the back of the case.
 

no they dont you can use a normal sata cable to bridge from adaptor to hdd and not directly conecting it adaptor

Thanks! For storage I have a 1 TB 7200rpm HDD laying around, that should work... And an SSD upgrade at some point is in the plans of course

Thanks! For storage I have a 1 TB 7200rpm HDD laying around, that should work... And an SSD upgrade at some point is in the plans of course