Both, Organic.maps and Oruxmaps, have implemented their own KML format to display tracks and waypoints.
Above tools help you to convert your route planning from Basecamp to your final product with a simple drag & drop. No self hosting nor any special programm needed. 

Start with your route planning in Basecamp. Here’s an example from my 2025 Balkans trip:

Export yours days route planning and drag & drop your GPX file either on

You may need to wait a few seconds before the program starts downloading your new KML file to your downloads folder. The file has the same name as your GPX file has but now ending with:
name-organic.kml
   or
name-orux.kml
The main screen displays now the tracks (in color you provided with your track) and waypoints. The advantage: You can immediately check what will later be seen on your mobile. 

The outcome of above planning viewed with Organic.maps on my iPhone.

Here’s my example GPX for you to test. Just download it.