Here are my "two cents" contribution, despite do not solve your problems, maybe could point you to another way.
- first you can reduce the colors of the images, instead of full color, you can try monocolor or posterized, but do not forget to change the image setting, this can reduce a lot of image size.
- second, do you know "iBooks Authors" from Apple? I already did some works with it and it has a good memory otimization for lots of images, BUT, it only works in IOS and you need to release the iBooks by AppStore.
I hope i have helped you.