Jonathan, I didn't notice the trucks/wheels dipping thru the frog, did you build up the bottom of the frog so they wouldn't or did Ross provide frogs that were made for 2-rail (not as deep as 3-rail)?
I didn't read every word on every post, so maybe you already mentioned this.
When I pulled my middle rail up last May I left the 3-rail wheels on everything because (1) didn't want to machine the engines wheels and (2) didn't want to change all my rolling stock with 3-rail trucks/wheels to 2-rail at the time.
I've tried some 2-rail wheels on a couple of cars, but they dip when going thru the frogs.