Tucker has good ideas, but I couldn't do the belt thing myself (heard it works like a champ, though). Luckily, I have two grown dogs who help watch Margot and she usually lets me know when it's time to go out. I make sure to reward her with a cookie when she tells me that she has to go pee/poop outside, in addition to praising her when she does it outdoors.

What has saved us was putting something that "smelled" like us in the crate w/our puppies. A worn, sweated on t-shirt. The girls found it comforting. Margot still barks like a banshee when she's crated and knows we are home. If we are quiet and she thinks we're gone, she calms right down. Do you know if he's barking when you're gone?