Here's what I have so far based on the advice you have all given:
LAN is configured as vlan0 (192.168.0.1) (VLAN ID: 1)
OPT1 is configured as vlan1 (192.168.1.1) (VLAN ID: 2)
Server is assigned 192.168.1.2 and has 1:1 NAT to a public ip address.
OPT1 Firewall rule: DENY OPT1 -> LAN
OPT1 Firewall rule: ALLOW OPT1 -> any
Does that sound right? This allows my private LAN to connect to my server (using it's internal network address [192.168.1.2]), but denies connections from the server to my LAN. I'm not sure how safe this is but seems like the correct method for what I want?
(NOTE: I don't need to connect to my server using it's public ip address. I only need to be able to connect to it from my LAN).