If a map file greater than 2GB doesn't work, why not reduce the dimension of the file itself?
Let me explain.
I made some tests using Mobile Atlas Creator making a map with the following features: google hybrid, 3x3 blocks with grid zoom 12 and zoom from 12 to 18 (not very big map, but big enough in storage terms).
I made that map using the "RMaps SQLite" option and the map file is 5.48GB (really HUGE for a map with an area of about 25km x 25km), then I made the same map using the "OruxMaps SQLite" option and the map file is 641MB (yes: 9 times smaller).
So: somehow the oruxmaps sqlite file is compressed and, in my opinion, some sort of compression could help both for the storage (less memory required) and for the use (the file can be opened).
EDIT: I looked at the MOBAC cache: google earth, google maps and google hybrid take 1.96GB of total space (1.78GB google earth, 1MB google maps and 179MB google hybrid); considering that I used the cache to make that map, how is possible that the rmaps sqlite file takes 5.48GB?