Thanks for mentioning this, I'd never heard of the CAST group before.
From what I've read, it sounds like it was a halfhearted attempt at mimicking the American ARG / MEU concept, but without the critical ingredient of proper amphibious ships.
I wonder if this is something that could be resurrected in partnership with the JEF group?
It'd be a big stretch for Canada to operate an ARG on its own right now, but I think its a worthy goal for a nation that's trying to become a genuine 'middle power'
Some learned experience with some Brit and/or Dutch amphib vessels would go a long way to figuring out how to make the Arctic Mobile Base concept more viable. (An idea I like, but acknowledge is a generation away in terms of tech and doctrine)
Maybe working with the SouKs on an ice class design of the Makassar class would be a reasonable first step, and valuable contribution to JEF?