map scale and printing size / resolution really are different things

how BIG of a file size do you want ?
i am currently sending a planetarium a copy of my 25 gig venus map and 8 gig heightmap for venus
the big one is 364 pixels per degree

also keep in mind the square rule
if you double the size you SQUARE the surface area

moving from a 2048x1024 px map to a 4096x2048 map is 4 FOUR times the work


so a continent ????
like Australia ?
Or North America ?
Or Eur-Asia ?

think about 90 to 120 degrees of longitude
and 45 to 90 degrees of Latitude