I am looking for suggestions in planning a route from central Texas to Portland, Me. I would like to avoid large cities and too many toll roads. Our schedule allows us 5 days to get there. Thanks
Looks like following bamcote's suggested stops would work well for you. I have stayed at Fort Chiswell and the RV park in Newburgh is well rated.
I would do a bit more than 400 miles the first two days as driving in the southern states will be easier and faster than in the mountains of TN/VA/PA and the traffic in New England.