When I create a set of maps for a road trip in Mapsource, I save the whole trip (mps for v5, gdb for v6) with a reasonable name, for example, colotrip.gdb (for colorado trip). So you would have several different mapsource files; colotrip, utahtrip, flatlandtrip, rockytrip, etc.
You could also rename the mapsets (right click on the mapset properties, then, you can turn off auto-naming), but I don't bother, since each trip has its own custom set of maps pre-planned.
When you upload to the 60C(S), just check the button to also upload maps, which overwrites existing map info with the new one.