I tried numerous times to install an LXDE desktop with the sid installer medium. It never reaches completion as packages are missing. When I did it a couple of weeks ago I must have been lucky to reach the end. I am now thinking about starting from stable Debian 8 with the Mint packages. I have to test whether such a system can be dist-upgraded to sid. I need a reliable way to create a Debian LXDE desktop, otherwise MintPPC users will need a lot of knowledge to get it all working. My goal is to make something which average Joe is able to install.
What about Debian 10, or even Ubuntu 16.04 (like Mint 18)? The archive keyring can just be bundled with the 10 installer, so the user won't need to do anything post-install.