HTTPS non standard port using VIP to work as ssl offloading VIP

I may be interpreting the question incorrectly.

To terminate SSL at the VIP you would configure a Client SSL Profile. However if your backend server is expecting traffic to be coming in as encrypted this alone would not work. Additionally you would need to configure a Server SSL Profile. This would need re-encrypt as it exits the LTM and goes to your server.

If your server can take non-SSL traffic you need just the Client SSL Profile.