I have heard that a good substance to use as the non-polar solvent is Naphtha VM&P. I have also heard that zippo fuel is naphtha. So, is it, and does it work nicely? I recently was gifted a zippo lighter, so it would act as a great cover for buying naphtha

I've used multiple brands of lighter fluid for extraction with success. Make sure to both check the label and perform an evaporation test. This is from the wiki:

Could you elaborate on the whole evaporation process? How I understand it, you use the naphtha to pull the DMT out of the sodium hydroxide, so it creates a layer on top. Then you siphen this layer into a different container, and place that container into the freezer. Then, the DMT will crystallize and therefore separate from the naphtha. Is this evaporation you speak of perhaps where the separation is supposed to happen? If so, how do you evaporate it?

the evaporation test is just a test to see if the solvent you are using will leave residue.

when you remove your solvent from the freezer and pour it off you will still have some solvent on your goodies, so you need to let that evaporate off. if your solvent leaves a residue then that will be left on your medicine.

to test if your solvent will leave a residue you do an evaporation test before you start your extraction. to do the test you drop 1 or 2 drops on a clean smooth surface, a piece of glass is ideal, then let it evaporate for a couple of hours. blow a fan on it or do whatever you plan to do for your final evaporation stage and then check to see if the solvent left any marks after it evaporated.
if the solvent left residue then you need another solvent, if it did not, then your solvent is good to go.