I would have, and probably have done so, played it close to what you did.
If you really want to do it 'right' then I think that you have to get them to agree to how to play it. Are they allowing the SH (short handed) team to play with four players (missing two), or play as four players (missing none).
The first option is messy, with ghost servers that cause a fault and awful front row implications, when the ghost players come to the net, it's an empty spot and no one is allowed to come up and play that spot. So either you have only two players max on the front row, or for half the rotations, there is only one player on the front row. What a pain.
The second option is what you seem to have opted for, then relaxed. There are three front row positions, so three players fill them each time, with only one back-row player.
Without line-ups, SK and LJ's, I believe that you gave them the best chance at a evenly officiated match.
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John
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