I modified a BD megamid for bike touring, but it was not quite the right answer.
i'm a big fan of the 'less is more' tarp touring setup
-that WAS a bike (and ski) trip -,
but i do primarily short tours.
For a cross country tour i would pack freestanding lightweight tent like the Black Diamond Lighthouse
, or perhaps a Golite Shangri-La pyramid
and mosquito liner.