The more rules the Convention sets, the easier they are to break.
Even the "no defense GJ cannot break" is useless... because if someone build a defense that even the combined power of the "Fen military" cannot break, you cannot enforce the rule anyways.
Boskone Prime was a heavily armed space fortress... it was still takes down by the Fen. So building something like Boskone Prime would be okay?
I would suggest not limiting defense at all. Because any static defense can be overcome with time.
Even the "no defense GJ cannot break" is useless... because if someone build a defense that even the combined power of the "Fen military" cannot break, you cannot enforce the rule anyways.
Boskone Prime was a heavily armed space fortress... it was still takes down by the Fen. So building something like Boskone Prime would be okay?
I would suggest not limiting defense at all. Because any static defense can be overcome with time.