No clue how good they'd be but rest assured they wouldn't shoot anything like I would.
I play golf a lot and I'm a fairly good player and I can usually guess my yardage (give or take 10 yards). Plus, 99% of courses have yardage markers on the course, I hope pros know how to pace it off like the rest of us mortals.
Remember, they all played public/private golf (without caddies) before making it to the "big time".
I don't think they'd have too tough of a time.