Salt and other electrolytes are absolutely key for me.
I like to use sports electrolyte supplements in pill form since I don’t like flavoured water - makes me want to eat, even green tea does that for me and I stopped ‘grean tea fasting’ when I figured it out.
Just be careful you don’t get one with dextrose in it. This is mine and I have a salt tablet too, but they can be a bit hard on the stomach, so I drink them with plenty of water.
Don’t think you want fiber, don’t know about CoQ10. BCAAs do have a small insulin response and technically you aren’t fasting in this case, but probably aren’t going to upset the apple cart.
I don’t work out. I can go for gentle jogs for maybe a couple of miles, but without taking in protein I find DOMS and recovery last a lot longer and I don’t see a reason why I’d be gaining. I feel pretty weak and I get out of breath fast and my heart rate is faster. Weights feel heavier, so I can’t get a decent workout anyway. I also find my electrolytes get out of balance, which is half the trouble, so I might find myself waking up at night with restless legs, low blood pressure or just insomnia.
I’m not fully fat adapted at this point though, and I have to work at maintaining my blood pressure while fasting. I never felt the need to fast the last time I was fat adapted but I’m looking forward to seeing it it’s easier and if I can run at least. I fell off the wagon and I’m currently fasting as a kick start back into it, also it’s a bit of a spiritual thing for me as well.
You’ll be different probably, and I hope you don’t have the difficulty I do, it’ll be fun finding out I’m sure. 