flyback RCD snubber
The bad thing with the RCD snubber is, that it's even causing additional losses without any inductive overvoltage. In my opinion, you can simply burn the spikes in the MOSFET's built-in overvoltage clamp, as long as it can stand the power dissipation. It's designed for this mode of operation.
The better alternative is a circuit, that recycles the leak inductance energy to the bus voltage. Unfortunately, it requires two (complementary) switches and two free-wheeling diodes.