I've been having trouble getting by "big-ass" mosfet, from an old class D amplifier project I'd been working on, working with the 3.3V output from the teensy (gate charge, threshold voltage etc.).
Eventually I managed to put together a circuit with a 3.3V to 5V level-shifter + totem-pole-driver to drive the mosfet. This mosfet will not be used in the final design but I will use it for a proof-of-concept breadboard circuit .
According to my first simulations I am able to reach around 80% efficiency, which I find fantastic. It's not too close to the commercial ICs but hey, it's 80% efficiency with only a switch, inductor, diode and cap.