Tripp Research makes compact mags in .40, you might have to wait a while as if I recall they are built to order in .40 (you said it yourself, it's odd ball), but they are good quality. I had some of those mags for my Kimbers in .40 and the mags were good to go. Tripp Research has changed around their website, you will probably have to call / email them:
Toll Free: 1.877.837.9445
E-mail: info @ trippresearch.com
I ordered mine over three years ago and I had to call in the order.