I've worked in cabinet shops where they have sprayed nitro-cellulose products without a spray booth or exhaust fan.( The good old days.) We had an overhead heater that would kick on and off, as well as a hot water tank. The key was that there was a large area for the fumes to dissipate. I have sprayed NC in my garage (attached). the biggest problem was that my house smelled like fresh lacquer for quite awhile. Kinda like painting you know what I mean. (After spraying I opened the overhead door for the nitro to dissipate). I have no open flames in my garage. You can spray nitro-cellulose outside at almost anytime of the year. If you do in extreme cold like where I the live it can cloud and could even fish eye or peel. That is why I like the water borne lacquers- very little smell and no volatile solvents. There is a knock down spray booth article in the Jigs and Tools section of the forum. "The fumes are what get you into trouble as they have petroleum based solvents." A little precaution goes a long way. Safety first. You can brush lacquer sanding sealer, very well.
The biggest problem with brushing lacquer is the set up time and the brush strokes. If you can purchase a lacquer type flow brush (Lee Valley tools had one or two ,at one time) You could eliminate some of the brush strokes. If not then I guess you would have to either scrape lacquer with no hook on your cabinet scraper or sand very lightly
until you get the brush marks out.
NOT EASY TASK.
Practice makes perfect. Any how that is my experience in brushing. You still get the fumes with brushing lacquer!! Have a great day.