I think a large proportion of those who would come would be 'wannabees'. I don't mean this in any derogatory sense, as most of us here were at one time without a smallholding, but desperately wanting to have one. So a Smallholding Show would be the place where people would get ideas, see the kinds of animals smallholders keep, what they grow, how they get an income - or IF they get an income. At that stage, people still have money to buy tickets to a big event.
As Rosemary has said, it really would have to be in the Central Belt - it's one of the penalties for living off the beaten track, that anything that's happening happens far away.