I believe there is NO time to use "Less than lethal" ammo.
If you HAVE to shoot, your life is in immediate danger, and you need to put the perp down NOW!
If someone is on your property and won't leave, he is trespassing - call the cops. Once he's on record for the incident, another arrest will get him more time in the hoosgow. If you shoot him with ANYTHING for mere trespass, YOU may go to the Graybar Hotel.