the interstate in that area has 'relatively' light traffic. wide shoulder of
smooth asphalt.

highway 90 even lighter traffic, but a fair amount of trucks. for much
of it you have a 3-5' shoulder, but it's a rough chip-seal.

the farm roads can be very narrow with no shoulder, and pickups wizzing
by at 75 mph.

will you be rushing through? any plans to ride big bend national park?

not sure about bus stations along the way, but there is an amtrak line.
unfortunately, many of those stations are no baggage car stops. carry
on baggage only.