How do people use npf with dhcpcd?

I have a couple of systems which use dhcpcd to get an IP address, but
also use npf for various filtering and other tasks.

 My npf.conf contains the below, which fails when rge0 does not (yet)
have an IP address

$int_if = "rge0"
$int_ip = inet4($int_if)

So far I have worked around this by having the following in rc.conf

if ifconfig rge0 | grep -q 'inet ' ; then
    npf_rules=/etc/npf.conf
else
    npf_rules=/etc/npf.boot
fi

and calling /etc/rc.d/npf reload in dhcpcd.exit-hooks, but this
seems... inelegant

Am I missing something obvious?

Thanks

David