You can have an arbitrary number of hidden volumes.

If an authority is convinced there's a hidden volume with information they want and that you are not providing access, having arbitrary hidden volumes is not doing you any good legally in the US and likely elsewhere. There are technical and non-technical ways to determine the probable presence of hidden volumes. Hidden volumes do not provide plausible deniability.

Might hidden volumes help you pass a cursory check? Sure. But if someone really wants your data it's not likely going to keep you out of a contempt of court charge.

wonderful thing about encrypted information, with the right key it can be decrypted to say whatever you want. So if government has decided that you have plans for the al Qaeda attack on your laptop... well, you do.

Now all that you have to do is prove that you either don't know or have forgotten the key that decrypts your random bits into a plan they will accept. How hard do you think it will be to convince an aggressive prosecutor/judge that you are innocent when you have no evidence (can't prove a negative) and the government has reasonable suspicion?

Only with a one-time pad?

A small key does not contain enough information to make the data decrypt to any arbitrary thing.