Wouldn't take much to write a quick jquery script to redirect everyone under a particular effective resolution. So for example the 1080P screen in my cell phone minus the controls is 360x592. The nexus 7 tablet sideways is about 960 pixels in width depending on the year. Id balance that against the minimum size that works for your front page.
Will want to make sure your using a method that queries the device resolution and not the window resolution.