Can confirm this will work with two controllers/players. If you don't have anybody around you can sing and play guitar/bass with both on easy. The song is relatively easy on both parts (Speaking for vocals and guitar. I imagine bass is easier than guitar.), but while focusing on guitar/bass I can see how someone wouldn't be able to focus on vocals at the same time. To remedy this, just sing though the song several times until you can get the basic tune down for the verses and chorus. Once you do this, you can work on the guitar/bass which is already easy enough. Another problem I can see happening is how to place the mic. I personally put my chin down, and tucked it between that and my body. The vocal system can pick up sounds fairly well with the mic placed like this really.
With enough practice 90% is very attainable on both parts by yourself.