If you are
moving to NJ - there are ways to bring your firearms with you. If you're
transiting through NJ - there are ways to have your firearms in the car (locked in the trunk etc).
However if you are
visiting somebody in NJ - in other words NJ is your destination on this trip - I see
no way for you to legally bring your firearms with you, carry or not - unless you have NJ documents such as Firearms Owner ID (which you can't get unless you're a NJ resident - and that doesn't include a temporary NJ hotel resident
).
In my opinion - if you (not being a NJ rsident and not having the right NJ papers) bring guns to NJ and get caught, you'd be royally screwed. Of course there's always a chance not to be caught. You pays your money and you makes your choice.