It's highly unlikely that will be acceptable. The point of the numbers is to identify your boat, particularly at the start and the finish. Numbers on the lifelines will be harder (impossible) to read at a crowded start and could well give you an advantage if you're OCS. If I was the race PRO I would not allow it.
Does your boat have any numbers on the sail? Often the sails list the hull number with your boat's make/model insignia. If so, just modify your PHRF certificate and register with the hull number, rather than those issued through USSA.
I have my hull number on my sails. In the photo below (yes, I'm in the back of this pack but I beat both of these boats during this regatta

), you'll notice my boat and the boat with the red chute both have the hull number displayed. The middle boat, another J/30, uses a USSA number.
