I do not think it is fair on the teams in the league by voiding the season, those that finished top three, Coventry, Rotherham and Oxford should be promoted and Southend and Bolton relegated, that is the position as the season came to a close and for the other leagues to follow suite if they do not complete the season.
The trouble is, Whitstable, in terms of the relegation battle you mention the two easy ones. Southend and Bolton were dead and buried, but who else goes down? Is it fair on Tranmere (currently in the last relegation spot) to relegate them when they're 3 points from safety with 10 games to play?
And at the other end, OK, Oxford are 3rd. But they're level on points with Portsmouth and Fleetwood, and a point ahead of Peterborough, Wycombe and Sunderland with anywhere between 8 and 10 games to go.
Without looking at the fixture list, it's quite possible that some teams will have already played most of the top teams and have (on paper) an easier run-in, while others might be in the top 6 but with a much harder run-in.
Given the doubts over whether next season could also end up being interrupted, my personal preference would be to just freeze everything as it is, and pick up where we left off whenever it's safe to do so. Although there I accept there's also the disadvantage that with players out of contract, by the time you go to restart some of the teams would be completely different with potentially a whole new squad of players.
If there's one thing that's sure, it's that there's no perfect solution that's going to suit everybody. So put it to the vote among the clubs, and go with the majority verdict. And then, most importantly, ensure there's some kind of rule in place for coming seasons stating exactly what will happen in the event of a similar shutdown some time in the future. Whatever's decided this time around, some clubs will complain. If the procedure to follow is written in the rules and clear to everyone before the season starts, they can have no complaints.