Ugh. I used to do nitrations in acetic acid all the time and never resorted to rotovap - after all, the stuff has a boiling point much higher than water. I would drown it, just like DMF.The best thing would be if you could precipitate out product. What's the MP of your product? If it's solid, just pour your reaction mixture over crushed ice when you're done, and recover crude solid by filtration. If you have a liquid, for 200 mL acetic acid I'd partition with ca. 400 mL water and maybe 200 mL hexanes or hexanes:ethyl acetate, drain off aqueous layer. Repeat three times, then wash with saturated bicarb solution: beware of bubbling. This way you aren't adding bicarb to pure acetic acid, which is a real drag.