Have you looked at the Kel-Tec Sub 2000 (.40 S&W) or their SU 16 (.223)?
Both are lightweight and fold up into a smaller, more easily transported package.
Note to left handed people on the Kel Tec SUB-2000, you get spryed with unburned powder as the shell ejects. If not for that, I would have kept my sub since it was so compact.