Any piano trio will be quite a bit harder than grade 8.
It's also one of the most difficult! Speaking of difficult, I just finished reading through the 'Dumky' Trio of Dvorak! Definitely beyond grade 8....
Are you going to perform it? If so, please record it! I would love to hear your rendition
In order to have a good trio performance, you must have excellent communication between the pianist and the string players. For this to occur, the pianist has to be able to play their part flawlessly, without looking down at their hands. His or her eyes are needed on the page and on the string players! To be able to play trio parts 'hands-free' in this manner requires highly advanced technique!
Try the Beethoven op. 1 no. 3 in C minor! Definitely leave Ravel, Tchaikovsky, and Dvorak for another day!