dns has nothing to do with ports..
If the server your trying to connect to is using a different port then the correct way would be in your ssh conf for this host..
Even if you were going to do some odd ball vip thing with nat your vip would be on the same network as the interface ie your 192.168.188 or your client would send that to its gateway IP since it would be off network.
The correct solution to your problem is to just use your ssh conf for easy access to servers.. You can put all the info you need right in this file.. Nothing would have to be done on pfsense, and you can take that file with you no matter where you go, etc.
example here is config I put in for a box uc.local.lan
host client
hostname uc.local.lan
IdentitiesOnly yes
user user
IdentityFile /home/username/.ssh/id_ed25519
0_1533825836971_config.png
that is exactly what you are trying to do - and takes all of 30 seconds to setup and cvan put in all the info you would need to make connection simple and easy.
Here this will help
https://nerderati.com/2011/03/17/simplify-your-life-with-an-ssh-config-file/