I'm thinkin', I'm thinkin' :D
If you cook them 6 hours and then throw them in the cooler, hmmm - they just might finish off even though they probably won't get up to 190 -- I'll say foil it and put it in the cooler and when the meat gets to 140 check it and then put it in the fridge -- below 140 you're just asking for it to spoil.
If it's not tender enough then I'd say put it in the oven on 250 and just let it go until it's fall apart tender. Keep it foiled with all the grease and juice.
Just my $.02 worth - your mileage may vary! :D
Southern Brethren BBQ Competition Team
"It's all about getting paid!" - Myron Mixon
"I love being hated in my hometown!" - David Hair
KingFisher Gator Rotisserie cooker, WSM, Stainless 5 burner with IR gas grill, Turkey Fryer, Weber JD Commemorative grill, slightly used Bandera chamber for future use as a cold smoker, Masterbuilt 40" insulated ELECTRIC smoker