None of these K.I.S.S. solutions is anywhere near as easy as the tool in the photo. By the time you have found 2 chairs and a piece of string, or jacked the front wheel to paint it (really?), you could have taken both measurements. It's just a ruler; no moving parts, no calculations, and it measures at the correct height automatically.
Anything that has to be assembled from multiple parts has lots of room for error. As for painting the tire, what keeps it from moving while it's jacked up? And when you roll the car to relieve the adjustment stress, each of these methods has to be repeated. Measure, adjust, check, repeat can be done in 10 minutes with the "ruler" with a very high degree of accuracy.