That workaround worked in 2014, but now "libfuse" seems to search under "/usr/bin" and not "/run/setuid-programs". The `DFUSERMOUNT_DIR` modification doesn't seem to work anymore. I think to reproduce all what is needed is `strace` with follow forks to see the software seeking "/usr/bin." And personally, I use an "AppImage" to invoke fuse that will seek for `fusermount3`

The author of libfuse will push an update in the future for libfuse to give up upon searching binaries by itself and only relying on $PATH simply, but that's not for now...