It can be done... I was in your position a few years ago. The year I completed my Grade 10, I also finished the Ballade (it wasn't up to perfection, but pretty damn good considering it was still quite a bit beyond me).
Look at some Grade 10 Repertoire - picking up the Royal Conservatory Repertoire/Studies from Grade 10 would definitely help; they cover quite a bit of stuff that comes up in the Ballade.
I found the toughest in the Ballade was the finger work for the right hand in some sections (arpeggios with double notes, intense scale passages, etc).
The Rachmaninoff Etude in G minor Op 33 is in the Grade 10 Studies book, and has a VERY similar ending to the Ballade. It also has a very nice cadenza, and quite a bit of technical work. It's definitely worth looking at (it's also free online, if you don't wanna get the book, at IMSLP.org)
I like the etudes in the RCM books because they are short. Some Chopin Etudes would benefit, but they can be quite long, and take a huge amount of time learning just one. The etudes in Grd 9/10 are usually 2-4 pages, and cover a wide amount of techniques.
Also look through some Chopin Preludes: I'd suggest the C+, G+, B+, Db+. I find the minor ones are either grd 6-7 level, or have tougher material than the Ballade.
Start looking through the ballade soon, pick out the easy/harder parts for you. Find what you have trouble with, post up, and get the easier bits under your hands. It's a lot more motivating knowing you're slowly chipping chunks away at the piece, and getting closer to finishing it.