REEL ESTATE

On winter nights, police would force homeless men to stay at the vast Fort Washington Armory at the northern end of Manhattan, but Nick Bernstein, The Saint of Fort Washington's location scout, had to endure three months of daily negotiations with city bureaucrats before the film crew was allowed the same access. To shoot in the turn-of-the-century armory-once a base for the Army Corps of Engineers and, since 1980, used as a 700- to 900-bed shelter for men- Bernstein used barter to pay the required location fees. Rather than cut into their under-$10 million budget, the producers gave pool tables, pianos, and art supplies to the city's shelters. What with the disease, the smell of antiseptic mixed with body odor, and the shelter's ''football-sized rats,'' SAG actors ''wouldn't go near the place,'' says Bernstein. No problem. The director hired 500 shelter residents as extras for $40 a day. Last month, regulations forced the city to cut back the number of shelter residents. But the leftover space won't go to waste: It's been reincarnated as a community sports center. And if anyone wants to play a game of catch, well, there are always the football-size rats. -BH