It’s pretty doable to find over-night accommodation, you just kind of need an approximate idea in the morning about the town/city where you’re going to spend the night. I’ve managed to find same-day bed-and-breakfast stays in cities like Salzburg and Trieste at reasonable prices. And driving in Europe is pretty great. Seeing the Alps, the Lago Maggiore and the Adriatic Sea on the same day is quite the nice feeling.