You're right, sorry about that. I figured if someone can confidently manage nr12 the rest is difficulty related to quantity.
I consider the op.25 to have some unbelievably attractive writing, they aren't commonly known. The f minor, E major particularly, c sharp minor and F sharp major drive me to the point of distraction. I'm currently in the process of listening to the preludes, all of them, since that's possibly the weakest area of knowledge with Scriabin's work for me personally, you might want to look at those, but it's a lot to listen to i find.
If you really want a sonata, you might be stuck with Beethoven due to the general demands.
Consider Debussy Images & Estamps Ravel Mirroirs. Faure too, Nocturnes or Barcarolles. Again those are lot to listen to. The 4th Nocturne i performed and still admire. The later E flat Barcarolle, and the 1st a minor Barcarolle along with the much later one too. I think the 6th Impromptu sounds more difficult than it is to learn, but i have not done that one yet.
Or Chopin 2nd Scherzo, that one is good for demands vs impressive sound.
If you have 3 months, i think anything big is fair game, and i'll repeat if you really like it anything is possible. When i first encountered the Saint-Saens toccata based on the 5th concerto i had trouble sleeping. Duchable plays it marvellously.