@Jack ***************
ok, I understand your predicament more now. Of course you are being a little demanding with Chiang RAI, as I would think Chiang Mai has flights in from more departure cities/countries. So as someone else mentioned - codeshares. As example you fly London Heathrow to Chiang Mai, but with a changeover in BKK. The last leg of the journey, BKK to Chiang mai will be flown by thai Airways, usually with a thai Airways plane/staff. But you'll have a single ticket and won't need to collect/deposit bags at all.
Or am I missing your point entirely ?
Finally, go hand luggage only if possible. That will change your life.