Kato 11-10x Power Chassis question

[velotrain]

I have a potential application for this where the length is not an issue, but extreme narrowness is called for.  The cast metal piece isn't a problem, but I'm wondering if I can remove the plastic "sideframes" with impunity?  I guess I'm basically asking if the axles are adequately retained by the metal chassis, or do the axle points also need to be in  the "journal box" ?