I'm probably not going to do anything with "height", because if I even fucking acknowledge the fact that there are idiots who have made themselves ten feet tall, it opens up a massive can of worms about what can and can't happen in a scene. What's worse about this is it actually makes it worse if I do acknowledge you're ten feet tall and make the scene work for you, because in the next scene along everything will go back to pretending you aren't. That's the problem with giving the PC a huge number of outlandish physical options in a nutshell.
Shoo my 10ft tall God Empress, you're alright. Shoo. filthy xenos yes. yes.
In terms of sexual mechanics, I agree with you. Though I hope for;
"While talking you hit the doorcase with your head."
"You hit the doorcase. Again. Anno snickers."
Int > 50% "You remember hitting the doorcase. Not again."
Dex > 80% "Thanks to your perfectly honed, gruellingly combat tested reflexes. Your forehead, by a fraction of millimeters avoids the doorcase. Anno looks very impressed."
Goo "With a wet splotch your forehead strikes the doorcase."
Dunno about virginity in general, it seems like it would unknowingly hide a lot of content.. and I wouldn't describe the game as "virginity-simulator".
As for the ways to implement meaningful shout-outs to character's thickness and tone without structuring the whole scene about it: NPCs commenting on them offhandedly is all that comes to mind right now. 'Ooh, #playername#, you are plump as a peach. Me gusta.' Although I'm certain there are a lot of other ways to do just that.
mmh, during dressing/undressing scenes? "You wiggle out of your way too tight [item]"
I am kind of hoping for a bit more "texture" (tone) descriptions for limbs like;
body-part-surface[smooth, translucent, hard, soft, rough, furred, glistening, lubricated, wet, gloved, clothed, rubber-encased, alien, heavy, light, limber, strong, verdant?, bruised?, swollen?, enlarged?,inked, tattooed, checkered, swirling, hypnotic, addictive?, meager, scaled, gelatinous, bound, constricted, dirty, clean, dripping, vibrating, sticky] ..mh the words flow
body-part-surface-belly+[toned, pregnant, trained, gravid, gigantic, epic-abs-bro, muscled]
body-part-fingers[claws, calloused fingers, long nails ]
"He roughly grabs your [] legs and.. "
"Your [fingers] slowly stroke.."
"Your [] toes curl .."
"Kisses your [] belly"
Otherwise mmh, I don't remember feelers/horns ever being used, but I don't care too much about that.
Having more scenes using long tongue / long ears / non-cunt-tail would be neat.