How's it going?
Sounds good and by all means try it and see what people think. However, if it's not a rally in a field, then are you thinking something along the lines of the Tramore thing with a hotel??
The Scooter scene is an eclectic mix of Ska heads, Skins, Mods, Rave heads, some punks even, ex-Mods and Soulies........which is great. If you go for a Mod Scooter rally then you'll be accused of elitism by your peers in the scooter scene because it will be seen as exclusionary and then there is whole nightmare of how you; excuse my language, but how would you "police" the event in terms of turning away folks who turn up in combats????
The scooter scene and Mod scene are two different spheres although there is a cross over of people into both but if you go to Afterglow in Belfast or Sleepless Nights you won't find too many people who go to scooter rallys there and vice versa; if you go to rallys you won't find too many Mods there that go to Sleepless Nights there, etc. so you have the tricky job of trying to bring together two different types of event because there are a lot of Mods that will not go to anything that has the words "scooter rally" in the title.
Sorry if that sounds negative, just giving you my honest thoughts. I've been a to a few rallys over the years (although it's been a while now) and enjoyed them but I know there are lots of Mods that don't bother with the scooter scene and plenty of scooter lads who don't bother with the Mod scene.