It is not just motorhomes being driven poorly, it is TT and 5ers. It is amazing to watch people with long trailer pulling into an angled pull through. They refuse to get over and swing wide resulting in cutting across the grass and curb creating ruts. We have seen more than one damage their RV simply because they do not know how to drive it.
I use the Satellite Pointer app. I periodically have to recalibrate the compass/location on my phone to keep it accurate. I also have to go into the settings on Satellite Pointer and tell it to acquire the location after we've moved. After doing #1 every few months and #2 each time we move, the app is accurate enough to use. You can Google on how to recalibrate your phone (differs depending on phone model and whether it is Apple or Android).
I have made numerous trips across country and have a few comments that might help.
First I am not a morning person so I like to take my time in the morning and typically get a late start. I am lucky to be on the road by 9am. Even then I usually plan for a quick fuel/pit stop in an hour or so. Afterwards I drive until noon or so, maybe 4 hours total. I stop for lunch and a 20 minute nap. I find a short nap does absolute wonders. After lunch and a nap, I typically drive another 3-4 hours tops. Then I stop again for another snack and short nap or end my day at that point. In the winter months with short days, I stop late afternoon well before dark. If I am lucky and drove on the open road, I might have made it about 350 miles. In the summer months I take my 4 pm nap and hit the road again often for another 4 hour session again stopping before dark. There are plenty of times I have driven 600 or so miles with some serious snoozes and without becoming stressed or worn out.
The distance depends on the driving conditions. Good conditions on a Interstate can mean lots of stress free miles in a single day. Because I never know exactly what to expect, I never plan and force myself into a schedule. Instead I start looking for overnight spots and alternatives a couple of hours before I need to stop for the day. Where I look also depends on the part of the country. Many States have absolutely outstanding rest stops; others not so much. Walmart Supercenters outside of urban areas are almost always a good choice. Truck stops can be good or horrible. In some areas the best choices might be local, BLM or forest service campgrounds. Again, it is best to have several possibilities in mind. Worst case I end up driving an hour or two after sunset. That is typically more exhausting than the hours spent driving in daylight. After a little experience on the road you can get really good at picking spots with nothing more than Google Maps as a guide.