Thanks for the responses. He was crate trained, but once he became fully potty trained and we put in the doggie door, we gave him more freedom. We still have the crate, but I think he would be really upset being put in it. I was thinking about allowing him access to the one room that has the doggie door and the back yard. So basically allow him to have full access to the yard and keep him contained to the kitchen while we are gone.
I agree he needs more activity. Just don't know if that will be enough to keep him happy mid-day. I wish he would chew on a rawhide. He loves squeaky toys, but rips out the squeaker in no time.