The most important thing is the track, yep. Even with no basemaps, that works.
Basemaps are nice for understanding where you are, predicting terrain ahead, and making unplanned detours (to towns, emergencies, etc). But they aren't completely necessary.
Some people will mark waypoints for major towns, springs, etc. But I think a lot of people just wing that stuff out there. I like to have waypoints for key spots.