TL;DR go for it with GM approval - the main caveat being to keep it light and fun.
Yeah, that's all cool. I guess I said that because as soon as you leave it wide open, people drop their OC from some other story in here that just doesn't fit and it makes the whole thing weird and awkward. I didn't want someone dumping a fifty page alien race description with planetary data, history, backgrounds, starship types, etc., etc. in here and trying to take over the whole group, turning it all "this is the lore I wrote, please follow it."
I don't honestly care what alien race people make up. I was hoping for original characters designed for this roleplay, but characters from elsewhere are ok, too, so long as the tone is light, fun, and entertaining. There are plenty of clubs for dark stuff. My main intent is casual, fun xeno sexual encounters, lots and lots of tentacles, and a sort of 60's sci-fi style hopeful naivete about how humans and aliens interact. Fun, light, silly, comical even... I'm trying to avoid antagonism, fighting, alien autopsies, and anything dark.
So yeah, I guess go for it. Your ployamorous alien character sounds good. Let her play with the tentacles. Humans as non-pets is fine, too. I didn't intend for it to be pets only, but I might not have been clear when I wrote the description.
I'll make an edit to the description because everything you said was entirely reasonable.