You'd like the LSS to catch the falling edge just before,
or as it crosses ground so that the body diode never gets
to conduct. That's going to be tough to control well, without
a zero-crossing servo loop (to take out FET gate drive
timing variation).
The FET could be backstopped with a Schottky or you could
look for FETs that have a low spec'd Trr, if you don't have
a control scheme that can keep the FET reliably away from
reverse conduction.
HSS drain voltage spiking only costs you Qdd per cycle, if
the HSS is off.
LSS diode you'd hope would cease conduction before
the next L-H transition, but if you push frequency or duty
cycle to where you have a low-side on time less than Trr,
you will push the whole stored junction charge from VIN
into GND. Presuming the LSS on resistance was unable to
quench the body diode. In any case the body charge will
be wasted, either from VIN or from the freewheel current.
Long story short, "don't go there", by whatever it takes.