So, I built my PCBv2 (without IMU, sadly, but that arrives tmrw!), and took it to my mates ready to try and fit a wheel somehow.
He tells me it is auto-steer ready as he used to have it on an old Trimble system. We pull the connectors for the solenoid apart, and my bench-psu squirts an ever-increasing voltage through it. At ~4v, it starts moving slowly, at 12v nice and fast. Well, isn’t that interesting… 
Fast-forward a couple of hours… ! We ran out of time, and in my excitement, I forgot to set the vehicle dimensions in AOG, and also because that IMU was missing, I presume that’s what was causing the excessive wander the faster we moved, tho now I’ve had time to think, one of the parameters I was pushing to try and stabilise it was the look-ahead, and perhaps with a wandering cab roof, doing that is counter-productive… Anyway, will be back with Panda GPS soon, and then we’re off to try again.
What a project! 
and well done to everyone involved with it !
Going to stick with USB just now, I presume Panda will still work that way?