According to some math that was done below you could do it if you jumped 56" and hit a serve 85 miles per hour and the ball had to travel 60 feet. Well luckily the ball definitely does not have to travel 60 feet. Many servers toss the ball in such a way that they don't make contact on their jump serve until they are 3-4 feet within the court. Secondly, if you were to attempt this feat you wouldn't be putting the ball on the end line, especially if you were jumping 56 inches. Now to be frank I'm not sure anyone is jumping 56 inches but people are serving close to 85 miles per hour, and Leon has definitely jumped 50 inches on a serve. And obviously this doesn't include players missing data on service speed(Miguel Lopez) who is said to be serving significantly harder than Leon which is admittedly unlikely. But I do think this is a feat that could be achieved, or at least one that I haven't given up on seeing.