How to breed hornworms?
The First Dragon
Once you have a male and female of five-spotted hawkmoths, they will breed freely! I agree with your keeping them inside a greenhouse, because they are a real menace to gardeners if they get loose. There are other species of hawk or sphynx moths; maybe not all of them are garden pests. You might consult with an entomologist at a college to see whether they have other suggestions about hornworms to raise. I know there is a hornworm I find in my garden that does not infest my tomatoes; but then maybe it isn't prolific enough for your purposes.
You will have to harvest the eggs from the tomato plants and raise the worms indoors with hornworm chow. Tomato plants are toxic and larva that eat them will be toxic to your bearded. Commercially raised hornworms that are sold as feeders are not fed tomato plants.