I'm glad to see that I have arrived to the same conclusions as you guys. I still need to perfect it.
For me the biggest problem is that it's not too hard to find such pictures of small- and medium-sized modern planes, but the older or larger aircraft are tougher to document in this manner.
One of these days, I'll give it an another serious shot and I'm sure I will have more success. My last attempt dates back to a few years with the Cessna 172 IIRC and were not very successful...