I wasn't aware the actual layout requirement varied by the age of the boat? Tpwd site has instructions on spacing and such, I'd follow it since they would be the ones enforcing it. If they got weird and wrote you a ticket you would have a good case to get it dropped by following instructions on their site. Honestly, I see tx numbers laid out all kinds of ways on different boats and never heard of anyone getting hassled over it.
If you're not living on the edge, you're taking up too much space!