Dog with dangerous tail?

this is for real. i have a boxer APBT mix without a clipped tail. it is like a whip no joke. when he wags it it leaves bruises and i have an eleven month old daughter who is now walking. put two and two together and it ends badly. he is an amazing dog and i would never trust any other dog with my child like i do him but he has been accidentally wacking her in the face and it has left bruises at times. we are always on red alert when he gets happy and i feel so bad tackling him when he gets excited so the baby doesnt get hurt. any way to maybe idk cussion his tail lol im serious he is way to old to have it clipped so i was thinking i could idk jerry rig something lol maybe a dumb question but ideas are welcome :)