You can use the commands split and cat for this.
split -b 725000000 filename (makes <700 MB chunks called xaa, xab and so on).
After burning and backuping you can parse it together with:
cat xab >> xaa (which puts xab after xaa, takes a while to run)
cat xac >> xaa (if the file was bigger than 1,4GB, do this after xab)
mv xaa orig_filename (to get back the original filename)
rm xab xac (delete the now unnecessary files after checking that the orig. file is ok)

Better test this before you delete anything if the files are really that important to you.
Note: You need to burn the xaa, xab,.. files before doing another file, alternatively rename them because the next run with split would make new files and overwrite previous ones.