Google Maps has an "Avoid Highways" option. Sometimes I create short routes directly on my Zumo XT.
When planning a longer ride, my typical process is as follows...
1) Plot route on Google maps (many folks also use scenic, ride with gps, rever, kurviger)
2) Once the route is finalized on Google Maps, I copy the link in the browser navigation bar and paste into
https://mapstogpx.com/ This site converts the google maps link to a GPX file and downloads it to my device - typically my laptop or iPad).
3) I log into my account at
https://explore.garmin.com/ go to the map option and then import the new GPX file as a track to one of my Collections there.
4) Once this is done, my Zumo XT will import the new track file when turned on and connected to WiFi. I can then convert the track to a route on the Zumo XT and I'm ready to go.
This may all seem a bit convoluted, but after you do it a couple of times it becomes pretty easy. It allows me to avoid basecamp completely and leverage other route planning options, like google maps. I know Ride With GPS (and other planning software) will create gpx files, but I find importing them into my explore.garmin.com account much easier than basecamp. I assisted a few folks on this year's Cannonball with this process and it worked well for all of them.