Here's how I rendered Switzerland in a(n in-progress) sub-mod for Death and Taxes;
It's still not quite historically accurate; I had to merge a lot of borders together to prevent adding too many new provinces to the area. Ended up adding only three provinces in the end; Neuchatel (was Basel for a while, but I changed it once I read that Basel got chopped in half by Napoleon), Aargau (originally a lot smaller and under a different name to represent the last remnants of the Kingdom of Arles) and Valtellina (the bit of Switzerland that's now in Italy). With this layout (in 1356), only Bern and Schwyz should be Switzerland. Chur should be held by "The Leagues" (well, the first of the Three Leagues didn't really get founded until 1367, but mixing them together's the simpler way to represent the various states in the area), Valtellina and Ticino should be held by Milan, Thurgau and Aargau should be held by Austria (an obvious boon for the player; connects Briesgau with Tyrol!), Vaud should be held by Savoy and Neuchatel & Valais should be independent.