I would do a tenderloin, some pork shoulder and a little bacon for the meat blend. You could sneak a little bit of lamb in there, it creates amazing complexity when combined with pork.
When I do Banh Mi, I use julienned carrots, daikon and cucumber, but, very similar recipe as you started this thread with.
For the sauce, find some Yuzu citrus, and some Sudachi, combine the zest and juice in a mortar and pestle, or just grate it together, then mix it into mayonnaise. You could add some sriracha, or chile oil, and that would make a great compound mayonnaise.