Baer went 20rds twice in July heat in an outdoor arena in Reno Nevada , stamina would not be a problem for him.
Baer completely outclassed. If Maxine was sh*thing his pants at the thought of a young Louis, he may need an extra Depends for a prime Frazier.
So we are talking the best Baer not the Baer who fought Louis or Braddock. Baer could fight a winning battle here. Hitting from long range and doing real damage and tying Joe up in close. Eventually a big right would land and the question then is can Joe take it? Conversely you have Joe at his best and he certainly had the characteristics to win against the best Baer. My vote would be for Joe to come on late to gain a 15 round decision win in a bout where he was losing over the first ten.