Choosing cities to go through may be one issue. Perhaps start a topic under the Regional subforums asking for routes and ideas. Sleeping and bike facilities might be part of the answer.

On a recent ride, I was only heading about 150 miles each way. Mostly outside of cities. So, I used a combination of paper maps, and Google Maps to choose an approximate route. Oh, also read the internet about camping.

The biggest issue was that I chose a mountain pass that I think I had driven 30 years ago. My maps showed it as a secondary road, but didn't specify road surface. Nobody I talked to could remember if the road was paved or gravel.

I ended going to the local Forest Service office. Unfortunately it was the wrong ranger district, so they didn't have any first hand knowledge of the road and current conditions. But, they sold me a very detailed map that covered most of my ride, and answered the question of gravel vs paved. It turned out to be about 20 miles of steep, winding one-lane paved road. Very low traffic. While I wasn't quite ready for riding the steep hill loaded, I'd love to head back there again, maybe with a lighter load.

I did create a Strava Route, but unfortunately it tried to choose a narrow busy road for part of the ride, when I already knew of a parallel alternative with much lower traffic.