Dying to read romance novels that have the heroine disquised as a male.?

I have read most if not all the novels dating 2000 or newer( if you believe the book is unknown to me then list it). I have also read all the novels written by modern best sellers. This includes Catharine Coulter, Linda Howard, ext. I am mainly looking for books from 1995 or older(going down to 1970's). I have been disappointed in my search for these books because I know it is a popular genera and was hoping I'd be able to find them. I was able to find some novels that fit this by reading the novel listings in the back of a book published in 1987. I would like westerns but it really doesn't matter. This lack of answers has been driving me insane for close to two years now. So I now leave the search up to you.