If there is no such spot, it's sometimes possible to land a stack with slow moving units like artillery in it, and then be able to split your stack since your infantry has movement left for some reason, bringing you close enough to the region capital to assault, with your artillery as reinforcements. But I doubt the AI does that :p

It really seems to go for undefended islands now though. I had both Russia and Venice sail half way around the world to declare war on me by invading Montagnais and Windward Islands respectively. How they could possibly know the garrison size of an island in the carribean is a mystery to me though...