Low? They are taking it all, if they are scammers! I don't even trust letterhead to be always legitimate orgn correspondence. You can print up anything on a computer. I don't even contribute to any charity, by mail, esp w a P.O. Box, until I ck address out w Better Business Bureau, or know it's from one I've been donating to for yrs!
Sorry, but I don't trust anyone solicitating now days, so I ck them out and BBB will tell u the % going to the cause & what they consider acceptable, which like u said is about 65%, which I think is really too low. 45% going into fund raising/overhead is a lot. In fact when I worked for the BBB doing Public Relations work, the acceptable was a tad higher!
What u are doing is smart & works!