Since recently it is possible to run Linux Mint XFCE on top of LXDE.
To install this one has to first install MintPPC. Then:sudo apt install task-xfce-desktop xfce4-xapp-status-plugin mint-xfce-default-settings
cp -r /etc/skel/.config /home/your_user_name
Logout and login into the XFCE session.
MintPPC XFCE is available for G4 and G5.