Welcome to the guild!
NASA has their Blue Marble textures, and there's shaded relief which has a good free texture too. These are basically satellite maps without clouds. You'd load a part into inkscape as one layer, then draw on top of it.
Do make sure that what you use is freely usable, you don't want to tangle with copyrights. NASA imagery is free (except their logo) as is everything else the US Gov't produces.