How to do google search on camping along a certain highway.

x2 RVparky app

rvparky is a great way to find RV parks and rest areas along the way. And rvparkreviews.com is a great way to find user comments about those parks.
I use google maps to check out smaller highways. I use it to find possible routes from point A to point B, then use google street view and/or satellite view to view the size and condition of those highways.
Another feature of google maps is their flyover. When you select directions from point A to point B there will be a small "3D" button beside "Driving directions to ____". Click on that button and you will get a complete fly over from start to finish. You can pause along the way and zoom in for a more detailed local view.

RVparky app or .com website. Put in a location, it will display campgrounds in the area. Move our wooden the app, more cg's appear.

It takes time, but I will use Google maps satellite view to find wide spots on the road, or possible pullout areas. Then use the little man to 'drive' the area and check it out further.

If I find something promising I'll grab its lat/lon, and put that in the Garmin. Be sure to get several as most of them do not work out - with being hilly or steep is the usual reason.

Of course this advice is moot if you're looking for a campground, but since you posted in Public lands, I thought that's what you wanted.

Someone recommended this app a while ago. I have not tried it. There are demo videos on the website.
Allstays