What I was trying to tell you was it will not 'crash' out if you use an aq. acid. It will go into the water layer however(3 acid pulls). If you add acetic acid to anhydrous methanol it will no longer be anhydrous, unless you have access to glacial acetic acid or acetic anhydride(not worth it). You could however use methanol and fumaric acid, citric acid, tartaric acid, etc. Or perhaps even dry acetone instead of methanol.
http://www.chemicalize.org/structure/#!mol=mesembrine&source=fp
The pH values should be sufficient however according to the pKa's listed.