I think you should use the center line as a divider for a huge infinity sign on top and 21 M on the bottom. No idea whether that has a bad effect on grip or anything. Not a surfer.
I just have one board so far that I use every day. Just wanna add some btc flavor to it. It’s 6ft 6inches. You can find many boards new or second hand anywhere. Adding the designs is a little extra work