We are wanting to jackpot this year to get my kids additional ring-time experience. But I have heard nightmares about sicknesses acquired through the jackpot circuits. Any advice on keeping pigs well during and after a jackpot show? Is there something you can give them as a preventative?

I would suggest showing off of your trailer. Make sure and use a probiotic to keep their stomach healthy. Plenty of water. T

The first thing to think about is biosecurity. Showing off your trailer and keeping your pigs and equipment separate from others as much as possible outside the show ring is the best you can do. The best practice is to isolate those animals after a jackpot show.
Making sure your pig is vaccinated can help you with the viral side.
Some people use prophylactic antibiotics and that can have some benefit it doesn't help with all the bacterial threats or anything viral and it's almost impossible for a vet to legally prescribe all but a few useful antibiotics for that purpose.
The other consideration is what can we do to put the pig in the best position to deal with a foreign microbial environment. We make supplements that help do that and so do a few other companies. Esterfied medium chain triglycerides have become a powerful tool in that tool box the same way they did for athletes.