One could try TETA (triethylenetetramine) as amine catalyst, using GAA, and once the reaction is complete.
This was done with 2,5-dimethoxy-4-methylnitrostyrene, and when complete, the entirety of the reaction fluid was poured onto ice. The result, crystallized near instantly, after which, filtration at the Buchner, and then washing with H2O cleaned it up nicely. Did a final recrystallization from ice-cold MeOH, and that removed the very last traces of pumpkin-orange, which in any case formed only a slight halo around the exterior of the mass of crystals, which were filtered off from the ice/traces of ice water from its melting, in this case, whilst Tsath' has never done it with a nitropropene, formation of crystalline product was immediate.