I have not yet tried this but may do when I get some plant material. Or maybe sacrifice some crystal in the pursuit of knowledge.
To the more chemistry literate please let me know if this is even possible as I may be off base with the idea. If it works Ill have a Fable Tek, but lets not get too far ahead.

From Wikipedia: Isopropyl alcohol is miscible in water, alcohol, ether and chloroform. It is insoluble in salt solutions. Unlike ethanol or methanol, isopropyl alcohol can be separated from aqueous solutions by adding a salt such as sodium chloride, sodium sulphate, or any of several other inorganic salts, since the alcohol is much less soluble in saline solutions than in salt-free water. The process is colloquially called salting out, and causes concentrated isopropyl alcohol to separate into a distinct layer.[2]

I believe that IPA dissolves spice more thoroughly than a number of the standard non polar solvents (NPS). If one were to use a generous volume of IPA instead of the NPS to get a good fast pull on the freebase spice, then increase the concentration of salts by adding salt to the point of super saturation, this would presumably drive out the majority of the IPA into a separate phase.

My thoughts are that as the IPA is a polar solvent it will mix fairly well with the initial solute (which shouldn't be too salty), so the extraction would be taking place at a molecular level, with the IPA drawing the spice out with the increased salt content, so they both change phase at roughly the same time, as opposed to shaking the crap out of a biphasic mixture to facilitate the transfer to the organic phase.

I have not seen the biphasic nature of IPA before but if the salting out method were to work it could increase yield and reduce extraction times considerably.
All constructive criticisms welcome.

IPA does separate in heavily salted solutions and so does acetone. But separation is not complete; in a 50:50 salt water:IPA mixture you'll get a ~30:70 separation, with the IPA phase carrying a fair amount of water.

How that would work on extraction? Sounds disastrous but worth trying.

This is an interesting idea. Have not tried this with IPA, but do know that if enough salt is added to a very basic H2O/EtOH solution, it will also form two layers.

But, even if you are able to get a satisfactory separation, it will not be a very selective extraction. You will pick up plenty besides dmt. It will need a purification step of some sort, which may prove more of a bother than using a NP solvent like naptha to begin with.

better off trying something similar with ethyl acetate, which only has 8.7% miscibility. (both IPA and acetone are 100% miscible with water).