That's the best age to take a few trips like that - I always wanted to drive across county but it looks like for me it'll be in a Winnebago.
Since I'm not on the route I can only volunteer suggestions.
A membership in AAA Plus. Gives her 100-mile towing for a year.
An inexpensive bike tire pump to keep in the trunk.
Pre-Paid nationwide cell phone - like TracFone (
www.tracfone.com) $100 for 150 minutes.
Some kind of camera for taking pictures of the trip.
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Inspect those axle boots.
Ken300D