Well worth a go. Another quick thought. As this will be sometimes working right down to zero dc volts, and at very low switching frequencies, the mosfet gate drivers will be much better if they are continuously and independently dc powered. The usual charge pump for the upper gate driver will definitely give you some grief. I used a pair of small mains transformer/rectifiers to supply isolated gate drive power.
Very interesting gapping the E core. Ferrite is still going to saturate at about 0.35 Teslas even with a gap. Good grain oriented steel saturates at probably closer to 1.3 Teslas. All else being equal, thats about three times the ampere turns.Cheers, Tony.