Dorval is one I considered, but I figured it would be a bit too close to the Oakville station. Although they are moving the Oakville GO across the street, so that creates a bit more of a separation.
As for Winston Churchill, I figured something closer to the Ford plant, west of Ford Drive would work. With the hydro corridor and stuff in the area, as well as relatively easy access to the 403, it would make sense to make that location the drive-to station for eastern Oakville and western Mississauga, as opposed to Oakville and Clarkson. That location also has the potential to connect with some sort of extension of the Mississauga Transitway, running either beside the 403 or on it. Buses only ramps from the 403 onto Ford Dr would make it a pretty straight shot to the station.
The other location is Lorne Park, which would need to be pretty much exclusively walk-ins and transit, and would need to be done in conjunction with a grade separation there.