victorytea, I know the wrap-in-foil-and-towels-and drop-'em-in-a-cooler may sound a bit chancy if you've not done it before. I took a leap of faith and had 30 pounds of chicken leg quarters that I did for a party. While I've since also done it with whole chickens by double wrapping in foil and towels and into the cooler, the leg quarters were put into foil pans and covered with foil and stacked in the cooler with towels and a couple pieces of cardboard to stiffen the stack. After FOUR HOURS in the cooler, they were still too hot to hold in your bare hand. So it really is a decent method to hold meat. Look up (google) "Faux Cambro". It's a culinary term and this proven method has been around for a very long time.
That being said, and if it's still not an option you're comfortable with, and temp that's BELOW your final cooking temp (and above 140) should be fine. I've held in a heated box at 150 for poultry. You have 2 enemies when holding. If uncovered, you run the risk of drying out the meat. This is a function of time. So a shorter hold time is more desirable. If you COVER the meat, then your enemy is time as the longer it's wrapped and holding, the softer your skin or bark becomes. So again, a shorter hold time is more desirable. If you cover and hold you can flop them around on a hot grill just prior to serving to crisp up the outsides.