Unfortunately Tesla no longer sells the 14-30 adapter. If they did, and you had one, there wouldn't be any point to this mod unless you were going to use a 14-60. Given that the car remembers amperages for each site, it's easy to set once to 24A and then not have to worry about it again. If you did forget, you'd pop the breaker in around a minute, which is not usually enough time for anything to get hot enough to worry about.
Tesla is (quite wisely) redesigning the UMC. The discontinued 14-30 (and 6-50) plugs are just the first step to deplete existing stock.
Relying on the breaker to pop wouldn't be my first line of defense to burning up some wiring.