We've done this before at Spiga, Bistrot Carraibes, L' Auberge Gourmand, and L' Estaminet. When we arrived, we made it clear we were there for only one course, and had no problem if they couldn't serve us. All four places welcomed us in and treated us as if we were ordering a full meal.
That night, Bistrot only had 2 open tables, but still let us in.