There is a long-running background sub-plot in the seasons leading up to Radar's return back home to Iowa in which he is mailing an army jeep back home piece by piece.
It is quite subtle, and often you only see him in the background walking by with a steering wheel, or sometimes packing another part etc.
After he returns home he sends back a photo of him sitting behind the wheel of his completed jeep on his family farm there and the rest of the characters find out what he was doing all that time.
This just feels so naturally like the plot of an adventure game so if anyone wants to use it then go ahead.