If you set up some rule like "you shouldn't go to plains bleh bleh" then if the person decided to go yolo solo and die in a bad place then they should expect to not get any help getting their gear back either. I think that would be punishment enough. Basically "go ahead and do dumb things but don't drag others into it" kind of attitude.

In terms of public portals it really depends on the type of game you are running. I am a believer that the person running the server is basically God and their rules are whatever.
That said it would be difficult in a role play type server to force people to make all portals public. If in a setting where the rules want people to stay together in one town basically and work as a team all the time I could understand forcing public only portals.

Sailboat racing obviously.
Target shooting from moving boat through a course.
Disk golf.


All in all I am personally not fond of rules and just put rules I would be ok with in general. I would never have rules like that on a server though since i don't want to play policeman and kick people etc