A search of Google patents under "ballast unloader" and "ballast plow" brings up a number of devices which (in the former) remove ballast from a flatcar deck and deposit it along the track, and (in the latter) redistribute the ballast already on the track. The term "plow" is used for the wedge in both applications, so there is precedent in the railroad industry for calling something other than a (dedicated) snow plow, a plow. Interestingly, there is a patent for a horse-drawn (road) snow plow that looks nearly identical to the EBT's wedge. So dragging a snow plow behind the motive power was not unheard of either.
So the EBT may have always called it's wedge things(*) a "plow", and they may have been used for snow too (FEBT oral history), but yet the EBT never owned a "snow plow".
As for the EBT's wedge particulars, it is the perfect height to mount to a steel flatcar and be able to swing up and not hit the ground (behind the hinge point) nor the car's coupler. I have tried to locate attachment points on all surviving flatcars cars to no avail.
(*) There is a photo of another one of these wedges set off at Rocky Ridge Station. Looks pretty much identical except taller.
William Adams