Ah, lots of memories here.
The main thing I'd say is that I would not just decide this is hard to deal with and the best plan is to avoid it. That's a great way to really feed the problem and to end up with a kid who is very difficult to deal with. This will cut down on your child's opportunities.
Thing to try: Get the child on your team where together you are working on deciding if work is appropriate. It won't take long before your child catches on that the elusive "just right" challenge can be very hard to find. The rule of thumb I read online that worked well for us: if you get 95% or more right we failed. You aren't going to learn anything from that and I don't want to waste your time. Same goes if you are going to get more than x percentage wrong. I will try to avoid assignments that but because you are an atypical learner (years ahead in some things, just your age in some things) there is a lot of guesswork and I won't always guess right. If I give you something that is way off that please tell me and we'll work together to find an alternative.
So, what you are trying to do is shift your child into the role where they are taking more responsibility. That may make them more sympathetic to the difficulty of finding appropriate assignments. And, it says the place of error is in finding the assignments, not in them. It will ultimately help you get better at figuring out that "just right" zone because they will be encouraged to communicate with you calmly rather than just melting down once they get started. This focus helps kid the kid in the thinking zone rather than deep in the feeling zone.
We combined this with lots of learning techniques to be able to stay on track when confronted with difficult material. Those including: setting a timer for x minutes (the child's choice) to see if they can make it through that time without a meltdown, learning to take stretching, exercise or breathing breaks, learning to set small realistic goals and noticing success when they are achieved, and working with outside classes and instructors where the child will be motivated to stick with it.
