Painting cowl panel

hmmm, finish in there is not a factor. Color and rust prevention is the only goal. What if we get creative.... Drop the fresh air duct on drivers side and shove a paint sprayer , hose and all (trigger locked on) into the cowl and across to the other side. Turn the air to it and let it blast. Tumble the gun as it is withdrawn slowly and covers everything. I think I would use a flat black rust ender product then let the overspray from exterior painting fall where it may just like factory.