You can run the whole race yourself.
You have to get out for the 5 minute manditory pit stop.
If you do the 2 hours yourself..
Get friends to do the re-fuel, its a pain
to get out, fuel, and get back in.
Get radios. You'll want someone to at least tell you how close to the finish you are.
Or tell you that the race has been over for
three laps now and its time to go home.
Don't expect to learn any more from a 2 hour race than a 20 lap session. I've found that the 20 laps are easier to remember and learn from.
Tom