I would also have some concern spraying a volotile material such as dope since most of the pumps and motors are designed for water based materials. although commercial rigs use an external pump so they may be ok, but that would be a bit of overkill,,
I dont think that you could get dope to spray in any manner acceptable without a lot of experimentation regardless so I think its a bad idea, brushing would be better in the long run, ( and I am a spray guy so keep that in mind)