I've done close to 20 Chumpcar and Lemons events, most 18-24 hours and the main thing i worry about is keeping hydrated. I use a cool shirt and drink fluids in car and can do 2-3 hour stints all day with a 3 hour break in between.
If i ever mentioned i wasn't drinking the night before at the team dinner I'd be booted off the team faster than an F1 pitstop.
I do find that i need a 'breather' each lap on the main straight and have to peel my fingers off the wheel...yeah i grip it and can't help myself. My stress level really only goes up during the darkness since you feel so alone.
I'm hoping to get out to Cresson in 2 weeks so keep your eyes pealed.
Current: SBM X5d, SPEC E46 racecar, Black FJ Cruiser, 1970 240Z
Former: '11 MCB E90 M3, 2011 Lotus Exige, 2003 350Z, 2002 WRX, 1996 Supra turbo, 1984 320i, 1987 E28 M5