I'm currently using the multiplatform suggested scheme:
the "export as a zip" and autobackup function of each environment, convert relative paths of each common module from .. to current dir, so the backup is not really useful to rebuild the full project
B4X:
+ root dir
common files
+ B4A dir
android specific files
+ B4J dir
pc specific files
the "export as a zip" and autobackup function of each environment, convert relative paths of each common module from .. to current dir, so the backup is not really useful to rebuild the full project