One version of the evap system does exactly that, just runs a line to the engine compartment and its left open. I wouldn't worry too much about a fire hazard as it doesn't really vent off all that much. When you are driving the air moving past the line helps to pull out any vapor present. Not necessarily the best system out there but it works. If you are worried about it, put a small filter on it (like they use for motorcycle vents).
70 Challenger RT 440-6, 73 Cuda (under const)
05 Durango, 99 Dakota, 01 Ram 4x4, 14 2500 4X4, 10 PCP Challenger RT, 01 Viper GTS ACR, 52 B3B w/330 Desoto Hemi, 70 Hemi RR, 61 Jeep FC170
9 x Challengers. AAR Cuda, 4 RR, 2 GTX, 4 Chargers, etc... (too many to list)