Prevent players from purchasing a nation specific ship, if they have any mutually exclusive nation specific ships in their inventory.

Example: If an Itani has any proms stored anywhere in the galaxy, do not let him buy any valks, until he goes and sells all his proms.

-1 to space police confiscating your private property unless...

Flying banned ships in specific nations space makes you a target.

-1 What are we moving the NSA into VO now?

I'd +1 this much as I'd +1 a fractional credit reset (I was once strongly opposed but now think it's the only way to fix the economy), but once it becomes possible to smuggle ships the restriction should be removed. This isn't a good gameplay rule, it's a good way of ensuring future good gameplay rules aren't circumvented by stockpiling.

-1, unless limited to same-faction inventories. Yes, I could see the Itani get miffed if I stored a Prometheus in one of their stations. But if I store it in a greyspace station, they should not even know I have it.

-1 on all aspects.

Your RP coupdn't have been more wrong: your nation (even in RL) always encourages you to *acquire* an enemy ship to win an edge on the war. In a meaningful RP, the acquired ship can be studied, its weaknesses amd strong points analized, used as spy vessels, or even tried to be replicated.