Yes. I do.
For me personally, I found it very very hard...nearly impossible to limit my efforts. I went through a really bad phase of the OTS and I was diligent about training at low intensities, but I'd start getting better and then the opportunity for a blow would happen, I'd take it, and then it would set me back. Being a senior karate practitioner, I'd also want to lead from example - holding back is really hard when you are telling people to push themselves.
Everything you have written suggest you haven't gone past stage 2 OTS meaning you probably are in better positioned to crack it, so that's good. But ask yourself how you would feel about taking 2 or 3 months off training and just going for occasional walks. How does that make you feel? Most people with early stages OTS find that very confronting, and because they can't stick to it they get to stage 3 and permanent and very frustrating damage to their system. A lifetime of looking over your shoulder trying to manage what you do.
The people who might be best to help you professionally will be Chronic Fatigue clinicians. Also sports doctors, which is where I went to first. But you might be able to sort it out on your own by doing a little research on Over Training. A good primer for the SNS is this:
https://www.linkedin.com/pulse/symptoms-overactive-sympathetic-nervous-system-you-headed-chad-oler
Phil Maffetone has a good article here:
https://philmaffetone.com/the-overtraining-syndrome/
But stage 2 and stage 3 are not sympathetic and parasymapthetic overtraining respectively. I don't know why he called them that, they are 2 different types of over training. Everything else in the article is correct.
I'd also suggest that because you have always had problems sleeping, you have probably always been prone to over-stimulated SNS meaning you will also overtrain easily. That's a bit of a bugger for you really. Could preclude your favourite forms of exercise. That said, what I have found is that if you are really well rested, have eaten well and take measures to recover well, the odd periodic big blow out might be ok. I have had big training sessions and had no adverse reactions at all. Sometimes its hard to predict.
If I were you, I think I would try rejigging my training so that I don't get my HR too high. So if you are doing weights don't do 3 sets in a row, switch around a lot with plenty of rest in between, try to be really zen and calm. I have a routine I do which works really well...I feel nicely 'used' but not over-extended, I do a heavy week and then a light week and a session doesn't last more than 20 to 25 minutes and yeah, my fitness has been very good. Very, very good at times. But running is the worst - which is a pity because I LOVE running. I go for a run I'm guaranteed a horror night in bed.
A question...do you have problems with cramps? I don't think it is anything to do with OTS necessarily, but I do...I have to keep on top of the electrolytes as well.