Nice to read this thread as we're considering doing this soon. Does anyone have experience in the last year or so? I've heard it's possible they do not allow Chinese cars into Thailand anymore. Could this be accurate? If that is the case, has anybody who's taken this route have an opinion if there would be a safe place to park a car and then take a bus for the Thailand portion?
Maybe you're on your trip already. I don't know about other places, but there are night buses between Kunming and Shangri-la. I was just through Pudacuo again last weekend. Much quieter, but on a sunny day still quite pleasant.
Another two guesthouses with a good history that I would recommend are Dragoncloud Guesthouse and Tavern 47. Tavern 47 is usually open through the winter and Dragoncloud said they will be this year. Some things are starting to shut down for the winter, but the number of people goes down too so no problem finding a place to stay. Definitely night buses, but the number of buses will reduce in the winter so check ahead of time for schedule.
We are in Shangri-la and I recently helped someone here buy and install fiberglass insulation. I ordered through Taobao, but selected a seller in Kunming. You can probably do the same and then get their phone number or find out where they are located and go there to pick it up. I imagine many of the large home repair markets around Kunming would have some.