I appreciate the point you asking people on DR1 in the hope that maybe you can rely on another members experience or even hook up with someone else in the same boat, but I think it would be a mistake to put so much confidence into our lovely members, just as much as I think it would be a mistake of any of our members to take you up in this instance.
I can't imagine you would go off the word of another and then confidently go through with it and so I think you must have someone coming with you to look over the child, you just want something for them to do to keep them occupied while you take care of business?
If you have a family member or close friend then drop them at the feria to spend a few hours horse riding. The lads there are good boys, and will look after them, but you still need a responsible figure you know well to go along, maybe 17+ year old., but even then I do not feel they are responsible enough alone.
I'd suggest to bring the ipad or something with a movie on it, waiting a few hours is not going to kill them. I also suggest no matter where you are in the world that you never take the word of others on anything when it comes to confidence on the care of your child. Even when my child is playing with other peoples kids I know, I make sure they are within my eye sight, that unfortunately is basic modern world parenting.
And besides everything else, you should know how strict courts are about child welfare. If anything was to happen, the judge would look to you for blame. You might think that they are not tough on welfare in DR, but when it comes to kids, these judges are hardcore, and could make life very unpleasant for you. Not that anything bad would happen, but they are always the famous last words before something bad does happen.
Take your child with you, plan ahead in future.