I found this great post on how to create routes and transfer them to your GPS unit on an Africa Twin forum. Having recently signed up for Gaia GPS online maps I was at a bit of a loss as to how to best use them. The subscription isn't cheap and I don't generally pay for any apps on my phone so I was very glad to find the following post from Matt On A Moto. Yes, it is a motorcycle blog but these mapping tips are just as applicable for mountain biking or bikepacking route planning.
I have copied and pasted it in here so that I have a permanent record of the detail. I am in no way claiming ownership of the material.
I would like to reiterate this is all the property of MATT ON A MOTO and you can find his original post by clicking on his blog name some 14 words back in this sentence.
I hope you find this of some help as I have.
Edit: I have deleted Matt's text as it simply would not format into the page on my blog. Please click on the link above to his blog for the full information.
Cheers.