I don't use BaseCamp (but MapSource) but here's what I do.
- Create one long route for the multi-day trip.
- Look at the route properties and find a point about 500 miles (that is one day of driving) from the last stop point.
- Look for lodging around that point.
- Make a waypoint for that lodging.
- Drag'n'drop the route line to that waypoint.
- Repeat the above as necessary until the destination is reached.
- Split the one long route into per-day sections.
Now the above assumes that
- You want a fixed stop point per day (i.e. know where you'll be sleeping). I know many bikers don't.
- That you can achieve a certain mileage per day. That depends on the terrain, traffic and so on.
I've been using the same general workflow for about a decade and it works for me.
You're lucky.