if he is working at 2nd to 5th grade at 4 years of age skipping k alone will not help.he is ready for multi grade skip or radical acceleration.many in this forum have that experience. Have you thought of skipping 2grades?how is he stamina wise? handwriting wise
best of luck
His stamina is typical four/five year old. He doesn't nap (hasn't since three), but he still gets silly-tired if he concentrates too long. Handwriting is done in all caps. He hates lowercase.
I doubt my husband would agree to a double grade skip. I think it would take some "heavy hitter" recommendations for him to agree to that.