It's implied that one can exceed the hull space limit in the ship design chapter. Any such components are exposed.

But it doesn't seem to specify a limit.

It explicitly allows overspending your power, and notes it takes time to swap over which components are powered and not.

So, is there a limit on over-space components?

My personal leaning is you can only overspace if you aren't overpower, but it's bloody unclear.

(And FFG, if you're listening, it's THE worst written chapter in any FFG book I've seen.)

Strictly speaking you could place as much on there as you want, but you'd run the risk of having all your external components destroyed. Expensive ablative armour is expensive.