I've seen another suggestion about removing a restricted slow on the Beluga, but that's considered too much of a buff, I think it would be good to switch a class 4 and class 5 restricted slot.
The problem right now is that it's very difficult to find a configuration where it's viable to put a fighter bay in the thing. You need a shield generator, and because of the hull mass, you can ONLY use a class 5 or class 6 generator, and that means you can only put the shield gen in one of the class 6 slots. That leaves you with one available slot for a fighter bay, so you have to sacrifice a fuel scoop. The tank is so huge, you're not going to want to bother with a class 4 scoop, and you can't put in a class 4 fighter bay (no such thing) and you can't put in a class 4 shield.
So that means you can't have a fighter bay AND do long trips.
If you made a class 5 slot non-restricted, and made a class-4 slot restricted, you could then squeeze in either a class 5 shield gen or a class 5 fighter bay, without significantly altering the balance of the ship.
The problem right now is that it's very difficult to find a configuration where it's viable to put a fighter bay in the thing. You need a shield generator, and because of the hull mass, you can ONLY use a class 5 or class 6 generator, and that means you can only put the shield gen in one of the class 6 slots. That leaves you with one available slot for a fighter bay, so you have to sacrifice a fuel scoop. The tank is so huge, you're not going to want to bother with a class 4 scoop, and you can't put in a class 4 fighter bay (no such thing) and you can't put in a class 4 shield.
So that means you can't have a fighter bay AND do long trips.
If you made a class 5 slot non-restricted, and made a class-4 slot restricted, you could then squeeze in either a class 5 shield gen or a class 5 fighter bay, without significantly altering the balance of the ship.