Slice the tomatoes in half horizontally, sprinkle each cut side with salt, and place cut sides down on paper towels for about 5 minutes. Hollow out the tomato halves, leaving sides 1/4 inch thick; remove seeds from pulp, and chop the pulp.
Place the chopped tomato pulp, squash, herb stuffing mix, basil, black pepper, and mozzarella cheese in a bowl, and mix until thoroughly combined. Stuff the mixture into the hollowed-out tomato halves.
Bake in the preheated oven until the squash is tender and the cheese has melted, about 20 minutes.
