you can use bait. We found that if you use a food product, make sure it is something your horse is familiar with and likes. If you use a treat, he may not even know what it is. be careful with really hard treats--I have seen a horse choke on one in the ring (at Nationals one year). We only use a parina product called 'Nicker Makers' cause they disolve easily so that is one does get caught, it can be disolve quickly with water. If I remember correctly, that poor little horse waited hours for the treat to disolve.
When my husband goes into the ring, he wears a hat and in his pockets you will find--nicker makers, bits of grass, bits of hay, pieces of crinkly paper and sometimes a little feed. He will use his hat and has even pulled his keys out to get their attention. At the last show, he was teased cause he grabbed hay in a hurry and stuffed it in his pocket. He was told he didn't need to bring the whole bale.