CharlieBrown, as far as I remember, the not sleeping in the sukkah was even mentioned in the MB as being due to either too cold in those areas (teishvu k’ein taduru), or because a husband should be with his wife, and it is not tzniusdik outdoors (also teishvu k’ein taduru).
Not aware of any shalosh seudos psak. I am not a Lubavitcher, but will ask maybe they hold you can fulfill it with a bottle of schnaps. Just kidding.
Joseph, your kashya of why not the Baal Hatanya also bothered me, and why not any of many other gedolim who have long passed away. I am not endorsing their position, I am just being melamed zchus. I feel bad that they have lost such a great person, and have been having a very hard time getting over it. One can only feel bad for them. It is not something to insult them for. They do much good in the world.