Concerning the 100 Mb file size limit, Dolby advised me to use the SVN feature from Lotrointerface to overcome the size limit when generating zip file directly from lotrointerface, but I don't understand how it works
Edit : I chose a third way, since I still had some leeway left: Reduce the pack size by hunting redundant big picture files by merging nearly similar elements across themes by using the JRR Core folder.