http://www.ridewithgps.com/
If you haven't seen this, you should.
Here's an example of a route I just drew by hand: (Mesquite to Bar 10)
http://ridewithgps.com/routes/4456845
This is where you'd find a list of my 'public' routes:
http://ridewithgps.com/users/259771/routes
You can also upload GPX files although it currently splits each track into its own trip. Hoping this can change at some point. But what you can do is draw your entire trip up here, and when it's all completed as a single track, export it as a .gpx file and import it into Mapsource or Basecamp and cut it up into the sections you want for your trip.
I don't know when/if the DualSportMaps.com site will ever be back online to edit tracks and such, so this is a very nice alternative.