Exhausting into the house is probably not a good idea unless there's AC and the smell is undetectable. However, the resistance due to convection is so small it would be negligible if there was a fan opposing it.Exhaust it right outside the tent, then you can install an attic fan that fits right over whatever type of vent there is in your attic. This way, the heat the comes out, isn't as concentrated and the noise level is down. You don't want to exhaust into the house, hot air naturally rises, so trying to push it down, is creating resistance. No matter what, the hot air will find itself going up, unless your house is flawlessly sealed, which most aren't.