For me, 'bisexual' implies androphilia, i.e. sexual or romantic attraction to men or masculinity. Many cross-dressers aren't attracted to men, but attracted to the idea of being a woman being with a man, autogynephilic for lack of a better term that's not 'invented' by Ray Blanchard. They're typically not interested in 'normal' gay sex or romance without cross-dressing elements.
'Straight' is not really a helpful term in this context. Does it only exclude homosexuality or also paraphilias and other forms of sexual 'deviance'?