When you say "Paleo", what does that mean? 1,200-2,000 calories isn't 1,200-2,000 calories since the macronutrient profile of the meal significantly affects how those calories are processed in the body.

You note, "I'm still working on controlling and insatiable appetite", which leads me wonder whether or not you are still consuming relatively large amounts of carbohydrates in the form of fruit or starchy vegetables.

Although the research is mixed, at least anecdotally carbohydrates are more stimulatory to the appetite than protein and fat.

The classic example, is, "Can you imagine eating a whole stick of butter?" vs "Can you imagine eating a cup of frosting?" While neither seems appealing to me, I know that I could much more easily eat frosting than pure butter. I also can't recall ever hearing anyone say, "Last night I ate one steak, and before I knew it, I ate the entire package!"

Seratonin release is also stimulated by carbohydrate consumption (research link here) and this could, in addition to the re-routing of blood flow to the stomach, be causing drowsiness. The fact that you mentioned "It goes away over night or post-workout", seems to point to this as a possible factor since exercise and other forms of stress produce an increase in epinephrine (rat study here) which would have a stimulatory effect.

I've heard, anecdotally, that tiredness after a big meal can be because of increased blood flow to the digestive system and therefore decreased blood flow elsewhere, but I don't see why it should last that long. Are you eating enough regularly? Just wondering why you're eating such a large meal, is it because you're IFing? Perhaps you'd be better trying 3 meals a day spaced out to see if it improves your energy levels. IFing can really drive some people crazy with hunger. Also, if you had leaky gut issues, long periods of fasting can adversely affect your probably already low gut flora.

Yes, I sometimes often get lazy after big meals, esp ones with lots of fat. If they are really big, I start to cold sweat as well.

Eating 1000+ kcal meals is teh shit! It makes me happy

Haven't noticed this myself. A three egg omelette with bacon and cheese just keeps me humming along. Do you notice a difference according to the amount of carbs? You may still have insulin management issues.