Does anyone have experience running an exclusive SMS Giveaway?

I am looking to run a giveaway with our SMS list only and have them reply with a keyword that would enter them into the giveaway, but I am having trouble setting up the backend for this to work seamlessly!

Some issues I’m finding:

1) I cannot find a way to work around the “When no keyword is recognized” trigger. I don’t see a way to add a new keyword auto-response nor a way for a “quick response” to satisfy not activating the “when no keyword is recognized” trigger.

2) I was looking to create a segment that equals A- is consented to receive SMS AND  B- “sent SMS” = �giveaway keyword] so I could see a list of people who respond with the keyword (and therefore choose a random sample to pick a winner), but I am seeing now that “sent SMS” only equals subscribe keywords and that won’t work either! (I don’t want to send them in a sign-up flow).

3) I also entertained setting up a flow, but again run into that I can’t seem to solve how to use a giveaway keyword as a trigger for events I want to happen (put into a segment and have a specific response or non-response).

Thank you in advance for all your insight, y’all!