A good cooler will hold for a LOOOOOOOONG time.
Last year, I helped out at chambersuac's charity cook and we had a coffin cooler FULL of butts (24 total) and after a good 7 hours, the ones that were still left were still showing 160-170 on the thermopen.
No worries man. Cooler that sucka!
Big JT's Smokin' BBQ Competition Team
MERRY CHRISTMAS BBQ BRETHREN!!!!