Crash Sites just spawn anywhere, They're not really pre determined, If you find one crash site on Server 1 It won't be there on Server 2. Like your friend said, Open fields are your best bet, often they're midway between 'civillization' and nowhere.
Besides having died from some random shot off in the distance of which I had literally no time to react and no time to think at least 4 times now. Its pretty good. Pretty vague but I'm not in one of those, typing moods.