Or modify mappero to use a folder that is not inside MyDocs. That should also enable using mappero when USB mass storage mode is active. The source code mentions this folder only three times, so one should be able to compile it using different paths. However, an external config file for that would be cleaner than hardcoding it, and one could upload it as new version into the repository. Therefore everybody who wants to use custom paths can do that without compiling it by their own. And, also quite important, no existing installation will be broken when the config file ships with the default path set to MyDocs/.maps...