USB Otg dhcp server that can set up gateway

I would like to set up a dhcp server on a pi zero that can route via guest PC automatically.
Setting up dhcp server is not an issue and I can get this to work using a subnet with only support for 2 hosts as the ip handed out will always be the same and ou can set gateway to that.
But dhcp retains locks sometimes and you end up with no ip been handed out.
Is there a way to use a larger subnet but have the ip handed out used as gateway?

Thanks