I think that's a great idea. And eliminates having to carry a folding table for dining in the great outdoors.
Do the hinges run the full length of the doors? If not, may want to add some more to help with the added weight of food, drinks, weight-laden elbows, small children or pets, etc.
And might be better to add swing-down legs attached to backside of doors vs holding up with chains....take more weight off the hinges.