Minimal control method is, use a coupled inductor to do combined SEPIC and Cuk in one fell swoop. Gives good matching and cross-regulation (doesn't depend on load currents so much; the regulated output still needs enough minimum load to keep the other side going).
Downside is, there aren't many coupled inductors available above 1515 sized SMT shielded-bobbin style parts; you'd probably need more than a few of those to get to 240W without melting anything. And the bigger ones that are available, tend to be more lossy, or poorly coupled (e.g. two windings on opposite sides of a toroid). So it may need a custom design. I think some 3637 PQ style parts are available though, which could do it.
Mind, good luck finding 3+ winding inductors -- but you can always use a pair of duals and wire the primaries in parallel. Use double the design inductance, since they reduce in parallel (two uncoupled inductors in parallel).
Otherwise, yeah, boost and invert is about as good as anything. Or multiple flybacks, which is basically the SEPIC-Cuk thing but worse (but it can be isolated, if need be). Or forwards.
Tim