criminals with higher wanted levels than 3 should be sent to dwayne

Mostly all cops want at some point lol

The only way to escape from Dwayne is from heli or boat that too it is very far from cities like LS and LV.

I would say that cap jail breaking skills at around 75-80% rather than sending criminals in Dwayne which is highly inconvenient.

-1

-1 that won't make the server enjoyable

It would be nice if you simply sentenced them there, which would make it impossible for them to offer you a bribe or forcibly remove you.
The island is there for something.
Furthermore, Donald Trump wants to reopen it.
+1