I'm not a fan of gas cars and motorcycles so gas bikes (aka, mopeds) is definitely not something I would like. Since you are not looking to pedal at all (sigh), my response below will probably not apply to you, but to add my 2 cents....
My wife rides a Specialized Vado SL ebike which is about 32# with rack and fenders (I weighed it). Main battery (included in weight) is 320 WH pedal assist and two extender batteries are 160 WH each (1100 g each or 2-1/2# ea). You can dial in how much assistance the motor provides, so if you only need an additional 60W on average, that would last 10 hours of you have two extender batteries. If you want an additional 120 W, that would only be 5 hours, etc
So, she still needs to provide leg power to go a long distance. It works for us, and let's her go the same speed as me with only an additional 80 W or so. It lets us ride together which is great.
Charging needs to be every night, though, and few campgrounds have outlets on a tent site. Takes a few hours to charge, so charging at lunch is not very practical, except as a small boost. So, mostly motels which is a problem if you don't know your schedule, don't have reservations, and if you stop in a small town.
I agree that bike trails can be dangerous, and I'm embarrassed to say that I've had more accidents on bike trails (usually at intersections with roads) than on roads.
We did C&O and Gap trails last fall (out and back sorta) easily. Cross country is going to be much, much tougher next summer, esp. the Western half of the trip. The planning is daunting...