Checkers
Boxer Insane
I think personally that you should gate him in the kitchen when you are gone with a puppy pad or news paper until you know he is old enough to hold it all day. Perhaps leaving an open crate in the kitchen as his bed is an idea
I do think it is cruel to leave a puppy in a crate for 8+ hours with no where to relieve itself, but as you said you arent going to do that
Another thing you will have to think about is feeding. Pups really need to have lunch, so whether you will leave food down for him or get someone to feed him is something you will need to think about until he can be on 2 meals a day.
As for leaving outside when he is older, it comes down to your dogs' personality. I leave Lily outside when im gone because she is not a jumper, she will not leave the yard (I leave the gate open when im home and she never leaves) and she does not get into mischeif. Whereas other people have dogs that will jump, destroy and escape. Yes it does get hot outside, but as long as there is ample shade, water and they can handle the heat relatively well, I dont see a problem with it
She absolutely loves the sun, so I hate to keep her cooped up inside when she could be enjoying it. Not all dogs are the same so you will have to figure out what yours is like before you make the decision, inside or out 
As for leaving outside when he is older, it comes down to your dogs' personality. I leave Lily outside when im gone because she is not a jumper, she will not leave the yard (I leave the gate open when im home and she never leaves) and she does not get into mischeif. Whereas other people have dogs that will jump, destroy and escape. Yes it does get hot outside, but as long as there is ample shade, water and they can handle the heat relatively well, I dont see a problem with it