The 1971's Tonys gave away 18 Awards on the air. And had 25 musical numbers - one for each of the first 25 Best Musical Winners (1 year was a tie - Fiorello and Sound of Music - so 25 shows in 24 years)
The running time without commercials was 1.57.
Add 15 minutes of commercials each hour. That gets us to 2h 30m
Thats 30 minutes to give the other 10 awards we have. A cinch. If they wanted to ..