I’ve done the trip from Middletown, CT to Seattle, WA and back a couple times. My recommendation is to enjoy the west for much of the time and book it once you get past WI. Lots of great trails in WA and a couple loops that can work your way back to I90. There are a few Boondocking campsites outside of Spokane, you aim for that for your first day. The second day could get you to western Montana and hit some forest roads and dispersed camping for a a few days. You could continue west through Montana, or swing south to Wyoming and see Yellowstone or the the Grand Tetons. From there you get lots of Boondocking in the state and then you could push towards the black hills, see Rushmore, Little Big Horn, Wall Drug and then head south and camp on the shelf of the Badlands and see the park for a bit. Once you are through the Badlands, it’s farm country until you hit the Dells in Wisconsin, lots of attractions and activities around there. Then it’s pavement with not a ton of scenery until you hit PA and you can enjoy the Pennsylvania Wilds there and explore. When you get to NY there’s opportunities in the Adirondacks and from there it’s a short drive to CT. These suggestions are based on the main I90 route, let me know if you have any other questions!