Can you expand on this as I do not understand this request. Your request seems almost contradictory: you have users that you trust enough to give control over your array AND your encryption password (and therefore access to all of the data) but do not trust enough to give them access to the GUI. Not to mention the root server password.
Additionally, is there a reason you have the server running but do not have the array started? If there are certain services you want to turn on or off on a schedule consider using the User Scripts plugin, or VPN in (does this situation happen often?), or a script that connects via SSH and starts the array that you could give them instead. Or, since you're giving others the encryption password anyways, could store the keyfile on your flash drive and copy it over on boot. The array would auto mount, still be encrypted and you wouldn't need others to know the password.
Food for thought.