Greetings,
It sounds like your boy is a great dog - with lots of energy to spare! (I agree with you - I have a Golden who is nine and is still our little wild girl - we often say that it would be nice to be able to bottle that energy and use it!)
Regarding your boy's digging while you are away. Since you do not describe any other signs that might suggest separation stress, this is probably a manifestation of all that energy (i.e. boredom) when he is alone with nothing to do. Since you were successful in the past with allowing him to have the living room, you may be able to redirect his energy and prevent the digging, without having to resort to crating. (A crate, while useful for housetraining and keeping dogs safe, is a very impoverished environment, so our goal is to always use it sparingly). To do this, purchase several stuffable toys, such as kongs, hard bones with open ends, or "buster cubes" (toys that deliver a kibble when the dog pushes or rolls them around). You may have to experiment to find out what types your guy enjoys the most. Once you have a small collection that your dog enjoys, these are always kept put away, and are only stuffed (or filled with treats) immediately before you leave. They are then placed in several different locations around your living room (hiding them is sometimes recommended, but I would be hesitant to recommend this in your case, as a hidden toy might trigger digging as he searches). At first, use these when you are away for very short periods (to ensure success). You may want to crate him on the occasions that you know you are going to be gone for a long time. The goal is to provide him with a "cue" that you are leaving, that is positive for him ("Oh boy, my fun toys are coming out!") and that will keep him entertained for several episodes of chewing/moving the toy around, thus preventing boredom. One caution - because he is a little guy, take care to provide a small amount of treats in these, as you do not want to upset his stomach and come home to a new problem!
Last, since this is a relapse of a previous problem, I would look at what may have changed in his life in terms of his daily exercise and interaction schedule with you. If possible, increase his exercise, especially prior to you leaving. It sounds like he may not go for walks outside of the yard - this is very important to provide to dogs because it gives both physical exercise and mental exercise (important to reduce boredom-induced problems).
I hope these tips are helpful - Best of luck!
Linda Case
AutumnGold Consulting and Dog Training Center
Thank you! Excellent suggestions!