Returns to the same airport do not qualify (even if there are two IATA-codes involved like BSL and MLH) as does non-commercial pleasure flying.
For me I just undercut my shortest route which was LAX to SNA at 36 mi with two equal sectors:
- KKN (Kirkenes) to VDS (Vadsô) : 24 mi
- BJF (Bâtsfjord) to BVG (Berleveg) : 24 mi
- with BVG (Berleveg) to MEH (Mehamn) the new runner-up at 29 mi.
All of the above airports are in northern Norway and were visited during the same flight on a Dash8-100 LN-WIR by WF enroute from KKN to TOS with 5 stops.