Experiments I did showed that gramine is only poorly soluble in limonene, mass spec comparison of crude methanol soak vs limo pull of one phalaris strain containing gramine is in the phalaris analysis thread in my signature.
Merck index also says gramine is not soluble in petroleum ether ( equivalent to naphtha), and DMT is. Im not sure about 5-MeO-DMT. Until summer I should have some gramine standards to do solubility tests and will share results
If I was to work with a plant that probably had fats and other unwanted compounds and I wanted DMT, I would either try to work with limonene and FASI, and then convert product like BLAB and see what im left with, or I would do an A/B and normal pulls with naphtha and freeze precip. If results are too impure, I would re-x or re-a/b. IMO defat is a very wasteful process that I would avoid, I would either work with fumarate precipitations or clean up the final product to avoid wasting hundreds of mls of non polar solvent.
If you bioassay, be sure to start with very small doses. Note that Arundo Donax in USA has not shown any DMT (neither related alkaloids such as 5-MeO-DMT) :
https://wiki.dmt-nexus.me/DMT#Arundo_spp. In india they did show those alkaloids, as well as bufotenine and a host of other indolic alkaloids of unknonwn activity.
I think the hard thing for you will be finding an arundo donax that first of all has the right alkaloids, and second of all has a significant amount of them. If I were you I would seriously look into TLC and colorimetric reagents. You can click my signature link to learn more about it.