The 1g / 50ml of hot naphtha is misleading and most likely incorrect, at least in the context of extraction. If you have a basic MHRB soup containing 1.5 grams of dmt and you make a 50ml hot naphtha pull (properly, with both the mhrb soup and naphtha heated to 70C etc etc) do you expect that you will need just two pulls to take all the dmt out? The answer is, of course not. There is a huge difference between a solvent dissolving an extracted compound and a solvent trying to pull said compound from a complex mixture such as an MHRB soup, this is why knowing solubilities won;t help you much in extracting.

Now, a question out of pure scientific curiosity: did you come to the 1g dmt /50ml naphtha number from your own experience or is it just internet hearsay? And how did you find out that you "can't seem to get anywhere close to this with d limonene"? What was your method of finding out? How much limo did you use and how much dmt did you retrieve?