I would delete this whole question but my answer may help someone else working with AI Controllers, Behaviour Trees and the like in regards to the WheeledVehicle.
Where I am setting the value of WhVehPawn in my controller in the above image, I do that in the actor class itself, as shown below.
The premise is exactly the same as what I was doing in my controller class, only I’m doing it from my Wheeled Vehicle actor class instead.
Something that I had to do to fix the Behaviour Tree not running as well this time was essentially adding a delay to my RunBehaviourTree node in the controller, as it was trying to run the behaviour tree before being assigned an actor to control (I assume).
My StartTick event opens a gate attached to the Controller’s tick function, from my gate I have a sequence, Then 0 goes to a DoOnce to the RunBehaviourTree node, Then 1 does the default tick functions such as updating throttle and steering for WhVehPawn.
I am very happy right now.