Simple setup

$ ifconfig re0 rdomain 1
$ ifconfig re0 10.0.0.10/8
$ route -T 1 add default 10.0.0.1

pf.conf:
anchor "cust1.example.com" on rdomain 15 {
    block
    pass proto icmp
    pass proto tcp from any to any port 80
}
pass in on rdomain 2 rtable 4
pass out from 10.0.0.0/8 to any \ 
    nat-to (egress) rtable 20