I’ve never used barricades either, but I think there are 3 relevant facts to them:
1. They add an additional 50% defensive bonus beyond that already added by a fortress.
2. Any unit that tries to go through a tile with a barricade is forced to stop even if it has movement points remaining.
3. Most importantly, they can be destroyed by bombardment.
As long as we don’t have to go through layers and layers of them, #3 makes them an inconvenience instead of a problem. Hopefully we will only have to break through 1, and then we will have smooth sailing. If we have enough bombers left after emptying a town, we can smash one barricade (or more, if necessary) with bombers. If not, we will use artillery – we have enough room in our transports for 102 units, but we only have 81 cavalry. Two of the remaining slots will be taken by marines, and we may complete a couple more cavalry on 208, but there is plenty of room for artillery if necessary.
As far as where to hit, I think Malice is the only landing spot in the north. In the south, I think our original target should be Glazed. I was thinking Apple Crumb, but the fact that bombers can kill citizens instead of destroying units may make that a problem. If we knock the population down to 1, then Apple Crumb will autoraze instead of being captured, and we won’t be able to unload our cavalry there. Glazed has had a cultural expansion so it won’t autoraze even if we knock it down to size 1.