travelling with cooked chickens

This scenario is on the borderline, if the travel time were the only factor. Generally, you don't want to hold foods in the danger zone (40 - 140 F / 8 = 4 - 60 C) more than about 2 hours. However, you have indicated you want to cook the chickens earlier, so that adds on to the time they would not be at a proper temperature if you tried to keep them hot.

The safest method, then, is to chill them properly, and transport them in a cooler packed with ice. Putting the chickens into zip-type bags will keep them from getting water logged.

See also: How do I know if food left at room temperature is still safe to eat?

Tin foil is not going to keep them above 140 F but a good cooler should. Use a cooler not much bigger than the chickens and pre-warm the cooler with boiling water.

2 hours below 140 F is the limit so even an hour should be safe.

Check the temperature when you arrive and like 1/2 way in transport.

Using a pre-warmed cooler is a great idea. Many of those ice-packs can actually be heated as well, if you have those type, you can heat them to add more heat to the cooler. I have also used foil wrapped bricks, heated in the oven, and put into the bottom of the cooler (on a trivet or something to prevent the plastic cooler from melting). I also put terry cloth towels on the top to absorb any steam that is given off to keep the mess at a minimum.

If you are going to do this very often, it might be a good idea to invest in a catering front loading food carrier (Cambro makes the one I use). These thermal containers cool down very slowly.