If alkalizing is the key, then potassium citrate can be used. This alkalizes the body, but unlike sodium bicarbonate and potassium bicarbonate, it does not affect stomach acidity. So you could take potassium citrate with a meal, and it would not affect digestion. Whereas with bicarbonate, you would want to take that away from meals.
Whenever I have tried alkalizing, whether using sodium bicarbonate, potassium citrate or via an alkalizing diet, I have always experienced a lightheadedness. I always wondered why that might be, and eventually found a potential explanation: there's some evidence that more alkaline blood causes vasoconstriction in the brain blood vessels, leading to lightheadedness.
So given that ME/CFS patients have reduced brain blood flow anyway, alkalizing may not necessarily be helpful.