Helping with local car show. Looking for advice/ideas

Take a deep breath and be prepared for controversy. The folks who do all the work are usually great....some of the participants are not. I did it for several years, but never again.
I am a member of a Sacramento Ca based Mopar club. We have an annual Mopar show that funds our clubs activities for the year. I have been involved with planning and day of show activities for 13 years.
First up: 90% of the work seems to be done by 10% of the members. This is the case with most volunteer based clubs. There are the casual members that creep in unannounced while everyone else is busy, these latecomers will stroll the show enjoying themselves while others really need a break! The ones that do work are rarely acknowledged by these lazy assholes that show up for an hour then go home. This happens at our show every year.
Secondly, some show car owners take themselves TOO seriously! They wig out if they don't get a prime parking spot or if another car scores better. The best that we can do is apologize and try to make corrections on the fly.
Thirdly, problems will pop up. A good staff will be able to correct them so that few people will notice or care. The key to this is to have a plan for every aspect as well as a backup plan if the primary one hits a snag. For this I mean overflow for parking, alternate bathrooms in case of increased attendance, a plan to get more supplies in case they run low and even something as unexpected as fire extinguishers for the unlikely event that someone needs it.
Me? I have tried for several years to have a few trophy classes a bit outside of the norm. I wanted an "Ugly Mopar" class where entrants could show their street legal, currently registered Mopar that is ugly for whatever reason be it wear, abuse or just terrible styling. I keep getting shot down on that one.