honestly, just put in what you want. (says the person that LOVES humiliation). if you worry about what others might want to read, you’re doing yourself a disservice because that’s been your fantasy for a while and you should do it just the way you would enjoy it.
Though as someone who has gotten very frustrated with people not responding to their writing, (for which I even changed the fandom) I can definitely relate with the worry. it’d be naive to always say ‘fuck the others just do what’s fun to you’ because reader response is def half of why it’s fun in the first place.
but you said you’ve been fantasizing about it for a while (I think? If I remember correctly?) and for something like that you should def do what you have envisioned all along and just let your gut feeling pull you.
and also as a last, pragmatic note: people that like to read consensual non con in the first place, and that are obviously into the humiliation aspect on some level will very probably get a kick out of watersports in that scenario as well.