No other plane can carry that much weight and release it for orbital launch at that altitude.
I just happened to be at that airfield by accident over a year ago at the time of first roll-out. I had not seen any pictures of this plane prior to the event and was really taken aback. As a kid whose dad and his friends were in WWII, the P-38 Lightning filled our comic books and thoughts growing up and to see such a giant double fuselage plane was breathtaking.