Well, part of the problem is that you didn't really say what about the original document it was most important to keep, and what was important to you and what wasn't. Is file size important? Is flexibility/zooming/reflowing important? Is preserving the exact look of tables, etc., important?
Attached you'll see what I probably would have done with it personally: I fed it through
PDFLRF, which created an image-based LRF. It would be viewable on your reader if held sideways fairly well, and it looks
almost identical to the original document. The characters are rather small, but I think still legible.
More downsides: these are images, so there's no zooming. The file size is enormous compared to the original document (more than 10x the size).
Obviously, getting your hands on the original .tex file and working with that would give the best results.