You didn't mention my favorite: buy a "Tokunai free" ticket for Y730 that allows unlimited use of JR in and around the central Tokyo area. Use it to go in and show it when you exit at, say, Odawara, paying the difference in fare but keeping the ticket.

Then to return from Odawara, buy a minimum price ticket and use the Tokunai Free to exit in Tokyo.

I'm sure this is not allowed, but the system isn't sophisticated enough to check -- and even if it does, your Tokunai free shows an entry with no exit because when exiting at (say) Odawara, the ticket agent never gets his mitts on the ticket to indicate an exit.