Looks like I found my answer:
5ml of methanol, ethanol, isopropanol or ecetone were saturated with SWIM's dmt fumarate, then the solvent siphoned off and evaporated. The residue was weighted. The results are:
Acetone : practically 0mg/ml (there was a very thin layer of residue left, impossible to scrape
IPA : ~1mg/ml. The residue was still too little to be weighted properly
Ethanol : ~5mg/ml
methanol: ~10mg/ml