I do a lot of long journeys with DD. As long as your DD's car seat has a good recline, if she's asleep you shouldn't need to stop to give her a break at 17m (just for clarity, with younger babies it is vital to have lots of breaks on car journeys in case others are reading this).
I have switched to doing all long journeys overnight. As an example, for the 300 mile drive to my parents place, previously I was setting off 8am then stopping at 11am ish for a 1.5-2 hour lunch break/run around/nappy changes, then setting off at 1pm and arriving by 5pm. The journey took that long because of traffic and the need for a good stop. DD had a lie flat car seat as a young baby so I didn't have to worry about car seat safety.
At around 18m I switched to setting off slightly before bedtime (6pm), usual dinner, bath routine and then milk in the car, and just getting the drive done in one stint, taking 5 hours, no stops at all (means tactical drinking plenty of water for you in the morning to hydrate but then not having too much to drink in the afternoon to avoid having to stop for loo breaks!).
I wouldn't consider putting DD in the front seat of the car. There are various safety issues attached to this and I think for a long journey you want them as safe as possible.
In terms of entertainment, my DD doesn't like screens much either so that would be pointless.
Also bear in mind that any entertainment you provide them with is likely to get dropped and cause upset when they can't get it back.
DD tends to have a couple of soft toys and a muzzie. If she gets fractious I sing or tell stories.
For daytime journeys I sometimes give her a magazine (we get a great one from Whipsnade Zoo which DD loves).
I avoid hard toys/books as in an accident anything loose in the car will fly around and become a missile.