By broilers I assume you mean Cornish Cross (Cx). They are different from Rangers and Dual Purpose.
Some people do but often not more than once. Several things were covered above. The Cx can be aggressive eaters. You may need several different feeding stations so all of them can eat. Many people want to restrict their feed later in the process so they don't eat themselves to death too early. Do you want to limit your egg layers? And the poop. Cx eat a lot so they poop a lot. You may be overwhelmed with poop management in your normal set-up. A separate area for them is probably a good idea.
You plan to sell them at around 8 weeks old. That pretty much means Cx. Rangers or DP will not be ready. Whether they are Cx, Rangers, or DP will have something to say about how to feed them. What shows are being held in October?
You are in Texas. I'd call your county extension office and chat with them. They are going to know about any shows and are probably helping 4-H kids get ready, whether that is feeding, grooming, timing, or something else. They should have local knowledge plus know-how. Could be a great resource.
Are you talking about as babies or to take to a show? In any case they can go a lot longer than that without food or water. The question about age is about how warm they need to be kept. If they are over five weeks that is not a problem. Younger and they will need to be kept out of the wind. No matter their age, they will poop so you'll have to contain them so they don't get poop all over your car. How to contain them will depend in how many and how old.