Sounds like you have a good road- trip plan...if you stop for a break and get a bottle of water, maybe leave a couple of sips in there and give it to her? DD can amuse herself for several mins just shaking an almost empty bottle of water and watching the water roll around in there.
Do you have an IPad or a tablet of some kind? I got a holder for ours for the back of the seat and then loaded it with some read it to me books and a few cartoons.
Benadryl? I'm joking...sort of. I don't have any other suggestions and I'm stealing your ideas, which are awesome, for a 7 hour drive I have at the end of the month. We do have one of those phone holders for our car and it works great.
Melissa & Doug has these reusable sticker books (I've seen them at Kohl's) and I originally bought them for my 3 year old during quite times but my 16 month old loves them just as much! We can get a good 30 minutes of her sitting with them (which seems like a lifetime to me!). I hate to even ask this but have you thought of leaving at bedtime instead? I'm guessing your LO sleeps 12 hours so you could take turns with your spouse and then stop for breakfast and let her run around then finish the 2 more hours. Either way, best of luck! I have 3 kids and none of them have liked car rides (nor do they sleep during car rides) so we've never traveled farther then 40 minutes so I give you a lot of credit for this adventure!
I think all your ideas sound good. Also maybe try putting snacks in different water bottles/fun containers so she can shake them. DD also has a fascination with bracelets lately maybe so that could be another idea too. I hope you guys pass lots of rest stops and she handles it ok!
Re: 14 hour car ride... Any other ideas out there?
BFP #1 12/02/11, M/C 12/08/11
BFP #2 04/06/12, DD born 12/20/12
BFP #3 06/09/14, M/C 06/15/14