Well here are the spoilerrific tactics behind my all-scout world-war victory for the final mission. I won't give step by step details, but I think anyone should be able to implement a successful plan based on the following.
spoiler:It's all about working with the game; taking advantage of any weaknesses in its opposition, while avoiding their strengths.
My key observations were as follows:
1. A scout suit cannot go toe to toe with the enemy forces.
2. Once detected by the enemy, scout suits have just one advantage -- speed.
3. The enemies forces respawn in this mission.
4. The enemy forces will hunt you down in this mission.
Brandt needs time to set the explosives, during which time he cannot defend himself. In heavier PBAs the typical strategy is to defend Brandt by engaging the enemy, drawing their attention and their fire. But what if Brandt didn't need to be defended?
Something important occurred to me: The enemies respawn in this mission. Respawn. And in proximity to the mission target. There's probably no limit to how often that can happen, but there's undoubtedly a limit to how many can be present at any one time. So... what if all those units are (a) already present, and (b) "otherwise occupied" when Brandt moves in?
It turns out that the squad command options give you everything you need to make this happen.
Not that you won't still have a bunch of work to do yourself, both before and after you bring your squadmates into play -- no matter how well I've executed this approach, the old "if you want a job done right" proverb still holds, so you should expect to be a critical factor in occupying the bad guys. But between the three of you, you can very successfully keep Brandt out of enemy sights.