I have hunted with a 64" and 66" out of a treestand. It worked ok, but I was careful about the stand placement, re: limbs.
Actually, the only time I had a problem was with my 60" recurve out of a new ladder stand with side rails. I took a practice shot to the left side and my lower limb hit the rail. Just another example of paying attention to the smallest details when hunting. I will still hunt with longer bows in the future.
Practice shots out of my treestand are important to me for checking clearance but also for getting my form right for shooting from higher levels.