texture file sizes

so im making a 2d game, and im using hand painted levels on giant Png imagefiles. will it backfire on me to use like 6000x 6000 size textures on a giant plane gameobject , there will only be one giant textured plane that being the background along with little ones for the player and misc foreground stuff and animated objects. not sure if this made any sense…

Maximum texture size is 4096x4096.