I love gifting food (via goldbelly or directly from a fave location) when people truly don't want more "stuff." One other idea that my SIL just got for my husband that might be applicable given your dad's roadtrip is the National Parks toilet paper from Who Gives A Crap. It's funny, pretty, and guaranteed to be used.

$37.50

carrying a jar of rainbow sprinkles on you

Keeping a Blanket in Your Car

Bring back the communal Punch

skin food

$22