Outbound traffic isnt blocked. You shouldn't need to put in anything for outbound ports on the trigger setup.
Port triggers are used to open inbound ports when certain outbound ports are used first. Game clients are good uses for this. You also wouldn't set up virtual servers and port triggers on the same ports. The virtual server page is to keep inbound ports all the time, triggered ports are for part time open inbound ports.
Servers usually expect inbound traffic first before they send out traffic.--
If it's important, back it up... twice. Even 99.999% availability isn't enough sometimes.