Omagari fireworks strategy

We are planning to drive to Daisen from Akita early morning on August 24th. Need to find parking within walking distance from the event.
After the end, I'm planning to drive East to Omagari By-pass and then south to Yokote to join Akita expressway towards Kitakami. It's desirable to be in Kitakami before 24:00.
Is it a valid strategy? I would appreciate any suggestions.

impossible by heavy traffic jam.
Free parking area(on road) full before sunrise.

http://www.japan-guide.com/forum/quereadisplay.html?0+101566

What about paid parking? Spending 24hours in a small car doesn't look like a good idea...

Also, when a major highway is stuck in my area (Toronto), I try to drive far away from the traffic using GPS and some common sense. Sometimes in opposite direction. Maybe someone can give an advice on avoiding the traffic jam in Daisen...

Found a great map (in Japanese) with traffic routes and closures schedule:
http://daisen.in.arena.ne.jp/hanabi/omagari/kiseizu.html
It's also available as PDF.

We arrived there around 6 am. Town-sponsored parking lots were not open yet. Parked our car on a private parking (2000 yen, south east side of the town). It took 15-20 minutes to walk to the river side. People were tent-camping in a zigzagged line in front of the gate that opens at 8 or 9 am to get free viewing spots. After taking our spot and marking it with tarp, we spent the whole day walking in the town, making pictures, buying food and sitting in our car with AC on. The show was great. We left early, 15 minutes before the end of fireworks and were able to get to the freeway without a major traffic jam. Arrived at our hotel in Kitakami around 11 pm.