Most of the Air Force top brass had tunnel vision about daylight bombing with unescorted bombers. The Brits basically said if you're crazy enough to want to do it, we won't stop you, but we'll keep bombing at night, thank you very much. It wasn't until the devastating Schweinfurt raids and the big losses of Big Week that reality finally slapped them in the face.
The P-51 was one hell of an airplane - and it could fly to Berlin and back to England.
We did daylight bombing because we had a secret precision bombsite that actually worked. Nothing tunnel vision about it. You had to be able to see the target to hit it. The alternative was inefficient carpet bombing a la the British, which could just as well be done at night but by itself did little but kill civilians.