Aligning massive PDFs in Trados Studio 2017

A customer of mine is trying to align two PDFs (source and target) in Studio 2017. However, since they are both so huge (Product catalogue approx. 750 pages) with many images, Trados is crashing when trying to perform the alignment.

I have recommended:

1) trying to get hold of the source files - customer says this is not possible

2) converting to Word and deleting images - customer cannot do this will take too much time

3) separating the file into smaller chunks and aligning them individually - again, due to the size of the files customer says this will take too much time.

Does anyone have any bright ideas of how best to align these files?

Many thanks in advance

Laura