Got some cranks in front of me and a Rockman freewheel (same thing).
Silly question, but... Is the bashring fitted the right way round? You mentioned it needing 2-3mm more clearance to the outer of the freewheel, the step that's meant to sit against the crank arm to prevent the bashring rotating is 2.5mm, the lip on the other side to give clearance to the outer of the freewheel is 1mm. Unless you mean radial clearance rather than lateral clearance?
In this case I can see how it could be very very close (see attached photo) - if you want to post us your right hand crank / axle / freewheel / bashring we can machine the bash to clear. No charge of course, and quicker than receiving parts from Hong Kong. Just let me know