I think it is possible with some good ventilation but the main element would be high ceilings, just like in genius' pic. The higher the better to give a place for the fumes to build up as far away from the people on the ground as possible. A nitro club up here tried to run nitro cars in a big indoor Go Kart facility equipped with a killer ventilation system. But the ceilings were only around 14 or 15 feet high and the fumes became unbearable. Even though the ventilation system was very powerfull and worked well for the Go Kart fumes, it still did not exhaust the nitro fumes fast enough. If the ceilings had been twice as high, there would have been more room for the fumes to accumulate up and away from the people, acting as a cushion to give the ventilation system enough time to exhaust.
Just my thoughts on the matter.