one thing I don't get, why not use a freaking machine gun mounted on the helicopter and fly along side your car, instead of dropping mines? Its cheaper, safer, and a lot easier (You can't even fight back!)
I think this game is a bit unforgiving with your time, perhaps in the sequel make optional missions that payout gold and exp?, sorta like how Sonny did things, make a no extra missions run have a special ending?
I guess Souls Policemen are definitely not the pragmatic kind of guys.