Charity Cruise Question

I need an opinion, from someone other than the know it all that I'm dealing with.
The American Legion I belong to has a car show every August. The show generally draws about 50 to 90 cars.
The show generally runs from 12 to 4 p.m. on a Sunday afternoon.
We also have a Needy Kids Program that, until this year, had a sponsor that was happy to give to us.
We need to raise some money to fund this program.
I suggested that we attach a "Fun Run" or cruise after the car show.
We charge an additional $ to the car show and we go on a cruise afterwards.
I've actually worked out some of the logistics of this.
Here's were I need your help/suggestions.
Do you think that having the cruise after the show is a good idea or do you think that the participants would to tired and we should do it on another date?
I'll list some pro's and cons for both arguments after I get your feedback. You may think of something that I haven't