Well the way that I plan to play/use my portable is this:
1) SSBM is a party game IMO, and as such would necessitate the use of 4 regular plug in controllers, which the built in multiplayer ports allow.
2) Where Super Mario Sunshine requires the use of the soft and hard press would have to be played on an external TV with a plug in controller, along with any other game that would require the double press.
So what I'm thinking is if I only need it for certain games, I'll just have to plan on playing on a full size TV. Which, IMO, is no big deal given the vast majority of the games I played and still play don't really require it.
Edit: Also THANK YOU! I'm glad someone had it to post. I've been trying to keep some notes on things as I go and I'll end up re-drawing that a little neater and I'll repost it at some point.