Sure, and I think that would send a message to all of your contacts that a new account is using that number, but I'm honestly not sure. If you have an active account (i.e. on a desktop or something), I think you can just change your number if that happens (i.e. get another temp number).

It's certainly more convenient if you use a longer-term number, but I think it's feasible with a throwaway number. Once your account is set up, Signal doesn't need your number for anything if you disable publishing that.