Making Ports harder in RSRD

I really like sneaking into ports and attacking ships there at the end of my patrol to use my last torpedos. But if I do it at night, and stay very deep on the way in I get past the destroyer guards easy.

Once I'm in the port itself there is no guard except deck mounted and shore guns, so at periscope depth at night it's kind of too easy.

Can we make it harder? I run TMO2.2 and RSRD.

I saw someone said they added more destroyer patrols and mines etc to ports, it might have been Armistead. Is it easy to do?

Can anyone share what they've done to RSRD to make ports harder?

Cheers