I've gotta say you are pretty daring to do a piece which runs for like 20+ mins in a row for an audience. Usually general audience cannot stay focused in long pieces and all your work has less "effect" on them in the long run. I would feel that the Sonata could be replaced by shorter pieces and be a lot more sucessful, but that is my opinion. But if you you have something amazing to show in this peice, and you have real strong confidence that you can keep the listeners interested for the entire marathon, go for it you can really make a good name with it!
I would simply leave it as Bach/Liszt. Start off with your selection of Bach's 48 Preludes and Fugues, connect Liszt to Bach by playing his transcriptions of Bach then blow people away with pure Liszt.
So you could start out with Bach, move into Liszt's writings of Bach, then into Liszt. It would be interesting to observe this newer piano master utilitse the old grandmaster of the keyboards music. I like to think of Bach/Beethoven as the older testament of piano (although Beethoven sorta exists more inbetween) and Liszt/Chopin as the Newer Testament. To hold two of these composers in contrast to one another, and then also show the line which connects them (Liszts trasnscriptions) would be good. Also Liszt's writings of Beethoven might be worthwhile if you want to put some beethoven in also.
Nevertheless you should have, if you are making Liszt such a prominent feature of your concert, have some Liszt transcriptions of the older masters. I think it would be very effective since you are putting Liszt on a stand, this would make his mastery of music a little more complete and educational to the audience.