"Art, I have no direct experience with the 302, but have you considered perhaps spacing the plates farther apart and enlarging the fields?"
To my experience the plates are optimally placed, although I prefer to set them at an angle for seated play, and the "fields" are adequate for play throughout a seven octave range and if one pushes it, more. No one wants the top octave anyway.
If one is concerned with the volume hand interfering with the pitch hand I have found no such issues and even if one did have such issues making the volume field tight and close with a range of two to three inches eliminates any possibility of interference and also enables staccato play. If you restrict the range of the volume hand its motion has little influence on pitch.