Yea I have, since this original post, gone back and enhanced the security. I'm currently kicking around the idea of enhancing kacars with a shared key system but I'd rather stick to the baseline. I'm just not sure how to offer a config download in the most secure manner.
Thanks Talisman57 that was the perfect wording to get me started. I modified the kACARS module to look at my custom module for matching hashes but only for kACARS clients.