Not to flog a dead horse but, its not that not all chaliponga leaves have 5-MeO-DMT, is that so far, it has never been shown to be present in any chaliponga apart from insignificant trace quantities, so it might be that no chaliponga leaves at all have it. Chaliponga stems might have a bit more (in one analysis its shown to be 2% of alkaloid fraction vs 98% of dmt) but still not significant enough to really do anything with it. Not to say there will never be found any chaliponga with significant 5-MeO-DMT but seems chances are pretty low.
The plant that has shown the highest 5-MeO-DMT content has been Anadenanthera falcata (aka Anadenanthera peregrina var falcata), which in a single analysis has shown around 3% 5-MeO-DMT content in seeds (5-MeO-DMT being 98% of alkaloid content). It is not sold by any ethnbotanical suppliers, but I got some through a friend in Brazil, and analysis shown only traces of DMT and 5-MeO-DMT, and it to be mostly bufotenine.
Another good possibility would be Virola theiodora resin (not bark), because snuffs made from this have been found to have up to 8% 5-MeO-DMT, but I hear from some people that didnt have success extracting from what some ethnobotanical supplier sold. If you try it out, let us know.
As for teks, general teks for extracting dmt might work for 5-MeO-DMT too, but until there is a good reliable plant source and some experiments are done, (or someone gets an analysed pure synthetic standard sample and tests solubilities) its hard to affirm for sure.