New marketing gimmick - Thundershirts, not just for thunder any more<gg>
The DAP may help take it down a notch, but it's not going to make this dog happy alone in his crate by itself. Crate games should help him be comfortable going in and out of the crate and staying there while you're around. When you go away, I'm not sure.
CU I think is so great for many things. You can also google Overall's Relaxation Protocol, which I think will help him. You can also try the RP in the crate, but McDivett suggests making the crate look different when doing the RP versus doing Crate Games. Drape it with fabric and/or a big fluffy pad versus a small flat pad, etc.
Also, try Through a Dog's Ear book. Interesting read and you need to do the music when you're around to start with, perhaps in conjunction with the RP before you just leave him with the music on. (besides, the book has 2 very cute r/w basenjis on it)
Otherwise, there are certain pharmaceuticals that may help while you install new habits of relaxing.
all the books should be available through dogwise.com or amazon</gg>