My opinion is that it’s not OK. The ordinance against parking in front of a fire hydrant is a rational precaution in case a fire truck needs access to the hydrant to put out a fire. Hence, it’s not a “chok” that one might avoid because of chukas hagoy.
Although one might might be confident that one can respond in time to move one’s vehicle should such an emergency arise, there’s simply no way one can be certain of that and lives are at stake.