SuperiorServers (Pls don't ban be for mentioning them.) Has this exact system in place however it isn't an addon, I believe that was custom made and coded by the Server dev himself. How it works is pretty simple:
There are 2-3 droid vendors that can spawn ships in different hangar bays. A B C or D
You MUST be a part of the republic pilots battalion to use them. If you are not part of the republic pilots or in a battalion/sub unit that can use the droids, it flat out won't let you spawn a ship/vehicle.
It only lets you spawn one ship/vehicle at a time. Once spawned, it won't let you spawn another until the previous one is destroyed or despawned by the ship spawner droid.
Once you are finished using the vehicle, you can park it anywhere and either use the droid to despawn it or press your undo button to despawn it.
It is even taken one step further and disallows certain vehicles to be spawned if the pilot is not trained for them such as a LAAT, ARC-170, Y-wing, TX-130, and so on. (I.e if the pilot is only trained for ARC-170, he may only spawn an ARC-170.)
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The version i'm seeing in the workshop link looks like it could work, but if you want it to not be abused, one or more of the devs are going to have to add some custom lua to it or configure it so that it restricts the usage of the bot to certain jobs, limits the number of vehicles spawned, or hell, you could even make it so that you have to be whitelisted by staff only to use the droid. I like the latter better because that allows pilot leads in battalions to hold better tryouts and they can blacklist/have blacklisted anyone that abuses the privilege or does a big no-no with a ship/vehicle.
I also believe it's possible to make it read the number of players connected and after it hits a certain number, it will disallow any vehicles to be spawned, and when the number goes below the limit, it will allow vehicles again. (But this can be super buggy as the number of players connected also counts people connecting that are not fully connected.)
So, what i'm saying is, the workshop addon should not be just simple plug and play, it actually needs to be configured to avoid potential abuse.