Be careful with the definitions of the timing numbers you
will use. Switching time may be the 50%-50%, rather than
the "reached zero" you'd probably prefer. You might also
care about details like driver prop delay and drive current
asymmetry when you're playing opposite switching
directions against each other.
I would favor a realistic simulation (if realistic switching
models can be had) because timing will follow Iload and
Vin to some extent (finite driver current, varying charge).
You might find, if your conditions range widely enough,
that you want "adaptive dead time" (meaning, forget a
single point closed form solution).