I decided to go de Orange Pi UNO way for different reasons; low cost, Gigabit ethernet outside the usb bus, only one usb 2.0 port.
My theory about the usb qrm from cables is that there is a RPI USB design allowing for this. I have tested one Rpi2B and two Rpi3B with identical results.
QRM is only generated when an active data connection is on, ie when a client connects to spyserver and start sdr#.
When I connect the airspy HF+ to a usb port of my Laptop and rin SDR#, no noise is generated with any of the six tested cables' using the same antennas.
I was considering the Tinkerboard SBC but as I'm runing on solar power, every mW of power consumption counts. Tinkerboard seems to draw more power than Rpi an Orange pi. Rpi3+airspy accounts for 630mA at 5V during an active connection. I have also taken additional power saving measures like turning off the on Board leds and the HDMI.