Sorry to double post, but thinking about it, if the npc is a top, simple variable switches would likely be sufficient to cover whatever the player is, as you suggested, and that shouldn't be an issue.
I should clarify that it's only content with females/herms I'd like to avoid writing. Nonsexual stuff can be enjoyable in and of itself, especially if you have some freedom to be creative with it. Sorry if I wasn't especially clear with the OP.