Codriver. For sure.
I was out there on my own and I'm pretty sure every day I lost at least 2 hours each day to "Sitting still desperately trying to get navigation to the next checkpoint" or "driving off into the wilderness because Waze/Google Maps decided that no signal meant they could just drop the route altogether" or simply checking/posting to Facebook. Having a second set of eyes and fingers to tend to the electronic needs of the event is pretty damned important even if you're not chasing points.
I also missed a checkpoint because the local parking situation was so positively atrocious that the only reasonable way to get it would have been to drop off a runner and orbit the block.
It's also tougher to get points for being funny/amusing on your own.
And then there's the "being so completely frazzled from driving" bit.
Book your hotels in advance. Preferably as soon as you know you're signed up and have the hotel list from Steve. Maybe even book some cancellable rooms before that. It's no bueno to get into a town where some other event is happening and discover that there isn't a single hotel room available. This happened to several teams in Memphis - there was some absurd Garth Brooks concert doubleheader thing that literally took over the city. I actually walked into my hotel and the first thing the receptionist said was "Sorry we're full, so are all our other affiliates, and I don't have any other recommendations". "Ah, but I planned ahead and made a reservation" was the magic phrase. Some of the teams that didn't reserve in advance actually drove part/all the way to the next morning's first checkpoint to find a hotel.
If the last checkpoint of the day is a good place to eat dinner, make sure you find out when they close and plan appropriately. If you fail to do this, you will arrive 2 minutes after they close. After your GPS sends you on a 10 minute tour of driving the wrong way down one way streets. I'm looking at you, Hank Williams Burger Bar.
When a meter maid sees you eyeing up an empty space and shakes his head at you, drive on.
Driver, Pit Monkey, Rod Buster and Engine Fire Starter