Keto and OMAD - longer fasts instead?

I lost 100 lb from a strict keto diet back in 2014, but I didn’t specifically try fasting in conjunction with that until now. I’m 22 lb over where I was when I originally lost weight and I want to get back there and be able to maintain the lifestyle better.

I began a week ago and have been on a 21-3 daily schedule. In my 3-hour feeding window I eat less than 15 grams of carbs and about 1600-1800 calories (eggs, cheese, peanut butter, meat, butter, keto - friendly bread that is high in fiber). For now since I’m trying to build the habit I am keeping my meals simple and specific. During my fasting period I am nearly constantly drinking water. I had a brief period of keto flu, but now I am feeling motivated and energetic.

My question to the group - can I do strict keto and still safely do a longer fast? I assume the answer is yes, because I am already in a permanent state of ketosis. It seems a lot of posters here do multiple day or longer fasts. The 21-hour fast that I’ve been doing could easily be extended to a full day, but I’d really like to try a 48-hour fast or more. Is the refeeding part after a fast any different with keto, or is it the same as any other standard diet? I’m aware of the electrolyte maintenance requirement for a long fast.

Additionally, are the longer fasts significantly more effective than a 21-3 if strict keto is adhered to or are they similar? It may be more sustainable for me in the long run if I get used to the “fast every day for most of the day” lifestyle, but if the longer fasts are more effective I’d like to do at least one per week.

Stats:

SW - 186 CW - 177 GW - 155

31/F/5’11”