I love labs...my last old girl had a 14 year run before I had to put her down. I AM a dog person, and I guarantee that I would modify this behavior without resorting to shocks, etc. but I've always had the "gift'. That said, there is no way in hell that I would make an older dog (she's not there yet, but soon will be) stay outside in the Fl heat...it's simply time to find a new home for this one if you can imo. That's just my .02 and I don't mean to pile on...the "dog pile"
ps: One of my best buddies had a black lab when I lived in Jax. When he got married, his wife banished her to the back yard
. About the age of your dog, the wifey came around, and she enjoyed her later years inside. They all don't chew, have seperation anxiety, etc...they are absolutely a product of their masters. If you can't do this...both your family and the dog deserve better....good luck!
ps: Mikester replied while I was typing. Nuthin' wrong with crating a dog at all (I only do while mine are small puppies)...heck, they sleep all day anyways