Offline Maps : no snail trail

If you have internet you can construct a detailed trek and get the line you want with turn by turn spoken and written instructions. Plan it, do it and save it all at once if you want, or do it in segments, with each segment done at a stop that has internet coverage.

I would suggest you do it in stages so you can easily edit, delete and add as required.

If no internet the process will be more laborious but you can approximate the above by creating waypoints and choosing towns or whatever that are not too far apart. You will get a trek made up of short straight lines, but no turn by turn instructions.

The Quick Start Guide and the User Manual will get you going.

The Quick Start Guide specifically addresses your question with a step-by-step example of constructing a Trek, which is what you want to do.