Good, that's the only way to play this one.
The other alternatives: if all parties had contested it would split the vote. Any united progressive candidate would have trouble winning in Clacton. An all-party backed opposition candidate would have been unlikely and would easily be painted as "the establishment" by Farage.
As things are: an independent novelty candidate might actually have the best chance, small as it may be, of beating Farage if they can capture all the protest vote (the absolute majority of Clacton didn't vote Farage in the last election). Or worst, most likely, case Farage wins a hollow victory unopposed by major parties, he hasn't made his point, things stay the same only now he's seen as wasting everyone's time.
