Nelson is typically home by himself around 9hrs each weekday as well. He is a bit older (almost 6) so definitely not a puppy, but we have had no problems. He was 4yrs old when I got him but was able to adjust really quickly.
I'm convinced that he sleeps the entire time I am away. On days I get home early I get a bit of stinkeye from him as I've interrupted the last bit of his nap!
Edit: He was crated to begin with, but after a few months he basically has all of upstairs to himself while alone at home. He has his beds, a couple of toys and also a fan when it's a bit warmer.