Allowing a pin or roller to move on a plane

We are having a discussion (arguement actually) here about the best way to properly simulate a part that moves on rollers.  With 4 pins through the part, one on each corner (pins that hold rollers) what is the best way to constrain them in simulation so that they are free to move along a plane?  With several of the available methods that we have used it seems that the constraints keep the C/L distance of the pins constant which gives inaccurate results.  The frame should be allowed to flex and the rollers follow but remain planar.  I think there are ways in beam mesh but we need to do this in a solid mesh.

Thanks,

SolidworksSimulation