If you want to be creative, get a creative/unusual name.
Give a kid a YOUNEEK spelling, you look like YOU can't spell, and your kid goes through life with his/her name misspelled.
My DH has a Connor in his class spelled "Konner." It's always misspelled and he's going to be stuck with that forever.
Just don't do it.
NN's are great. So call him Jax, but still SPELL the real name Jackson. You can shorten it to Jax either way.