The poll workers can and will force you to do that. They take great pride every election in telling the local TV news types doing human interest stories that taking pictures of ballots accomplishes little other than pissing off the 80 year old poll workers who now have to work even harder. Some probably do successfully slip thru the system.

Another option is making a fake ballot. The local newspaper used to helpfully publish their suggestion of how a devout left wing progressive would fill out their ballot. They're currently the establishment, so they're likely to be the largest problem, and its solved right there.