I've been using Gaia and Rever (as in gassing it) paid subscriptions to plan and execute trips up to a couple hundred miles long for a few years now. Trial subscriptions work well and both have very adequate free versions. I've lead driving events of similar lengths for our Miata Club. Both can record your actual drive, though neither allow easy edits to those tracks. Refining a route over time means replanning your track as a route, which can then be modified.
Rever has a friendly user interface and a wide selection of maps. It doesn't use Android Auto, but can use Car Play. It has a "twisty roads" option for planning that works very well. Rever is targeted to the motorcycle community but works well for autos. It has an excellent follow-route continuation ability after a phone reboot. Gaia leaves it to you to figure out.
Gaia displays very nicely and used to have base maps that showed topography nicely, but then they improved it and it's hard to see any topo lines now. Gaia is targeted at the hiking community and works okay for autos. They were bought by Outdoor a year ago and I believe that company treats Gaia as merely a checklist feature in their suite.
A major advantage for Gaia (and possibly Rever? I'm not sure) is that it shows the names of villages, towns and cities as you drive. Google Maps is poor at this, showing no information for what is around you.
If you have time to plan your route I recommend that you use a laptop/PC for it. You can export the route from Rever as a .gpx file for import into Gaia and display it on Android Auto. Gaia also expires routes but I don't think Rever has an import. Do not expect easy planning or full features from their mobile apps.
I have not used either for off-road planning. Rever has an AI option for off-road planning. Gaia has a map that shows unpaved roads but this relies on data they do not control and at best is a good guess. Some roads have since been paved while others were never identified as unpaved.
Both apps use external sources for their map data. It's pointless to tell them that their routing is wrong (a rare and minor problem) because they have no control over the geo data. This resulted in a routing through a restaurant's outdoor seating area that Rever insisted was a road. Gaia once routed me along roads that don't exist - one was a farmer's driveway and another was a fenced farmer's field. These latter two were pretty major issues and I reverted to interstates to solve them. But in 11,000 miles of cross country driving this was the only major problem.
Both companies have an extremely small coding staff. Rever has one person I think and I think Gaia may have two. Rever is easier to deal with while Gaia is friendlier but more skeptical of user reports. Both coding organizations lack adequate software development processes. Expect bugs in new feature releases.
I've spent a lot of time with customer service for both. Gaia is extremely poor in that area. Their saved routes were spontaneously being corrupted. I reported the problem and it took nearly half a year to confirm that it's a bug. I got so frustrated I told them I'm quitting and they gave me an extra year paid subscription. I no longer use it to plan but things may have improved.
I went on a 72 day solo drive around the country this year and planned routes on these two apps only on the first days. It was just too cumbersome to continue doing that daily. The routes were very nice roads and driving progress was extremely slow primarily due to lower speed limits and a LOT of curves.
For the remainder of the trip I used Google Maps with the "avoid highways" option turned on. This often gave me very pleasant and uncrowded routes but it's not perfect. Once it put me on Alt-90 which was a well paved fast road running parallel to I-90. Same view as the interstate and same speeds. But that was an exception. Mostly it found very enjoyable roads. I had Gaia in the background to figure out what city I've entered.
Finally, I've found both apps can heat up (and occasionally overheat) my phone. I recommend removing phone cases, exiting all other apps, and if driving away from cell coverage, using airplane mode to keep the phone from using high power transmissions to find a phone tower. In our Honda, I pointed the air vents at the phone in a cup holder and that was excellent while using AC.
The best way to improve your success is to have a passenger that understands the app and how to navigate and can provide clear communication during critical phases of driving (for example, entering an intersection with more than three exits). The more you practice together the more smoothly things will go on a longer trip. My wife is invaluable at our navigation and we have a fairly clear and concise method for communicating directions, e.g., "In 0.2 miles turn right [at xxx]". Sounds dorky but it eliminates having to extract crucial information when each instruction is phrased completely differently from the last. Air Traffic Control and pilot communication works like this. Not everyone is good at this however so be patient.
Good luck on your trip!
I'll also need a mount, so I'll have to do some reading on that.
