Going to echo with my experience of doing keto for about a year. It helped me deal with cravings and satiety a ton. Doing a multi-day fast was easy. I wouldn’t say keto is nonsense, just that I ultimately couldn’t make a lifestyle out of it cause I couldn’t find a way to make it work with cycling. I saw the same HR spikes you’re mentioning. Probably could have experimented with blood tests more to better regulate carbs, but poking myself for blood didn’t work out(I’m squeamish for that stuff).
I mostly switched to kettlebells & rings during keto. Keto was fine for how I structured those workouts. Really really started to miss cycling after awhile.
Recently started up Renaissance Periodization and have been very happy. I’ve lost more weight faster and get to cycle. I’m the type that needs a very prescriptive structure. It just fits my lifestyle and personality. I hate to throw the baby out with the bathwater on this one, but a diet that fits your wife’s lifestyle might not fit yours.