I have a couple of small sycamores (less than 4' tall) that the deer keep eating the tips off of each the winter. It's caused the trees to have very poor form as it tries to recover by sending out new branches to replace the leader. Last year I cut an autumn blaze maple with the same problem off at the ground and it grew back almost 8 feet in one year, with a nice, straight trunk after I took care to keep just one sprout and cutting the rest off. Would a sycamore respond similarly?