I like the idea! My opinion is "with tractors" would be better, but either way sounds fun. I don't generally go more than a couple hours drive from home but could go farther. Being a truck driver I pretty much get my fill of steering wheel holding and trips lose some appeal because of that.
Another option is a meeting within another already established show. This is how the Gravely club does their annual "Mow-In".
An area of the show grounds is set aside just for the Gravelys. Mow-In's are held in a different location every year so everyone has a chance to attend at least some years without a 2000 mile drive.
While I'm thinking of it, the 34th annual "Macon County Flywheel Reunion" Macon, Missouri is featuring garden tractors in 2014. Dates are July 24-26 2014 at the fairgrounds on the south edge of town right off HWY. 63. This is a well run show that treats exhibitors right.