I think boot camp is the more prevalent term in Aus and overcoming that hurdle could be a bit of a battle.
When I search 'fitness camps' I can see a couple of results for boot camps, most predominantly boot camp dot com .au
GAKT doesn't show too much difference between the two terms (100 fewer local monthly searches but higher competition for fitness camps when I looked).
Having said that, I still think it would be an appealing buy for a motivated buyer. I don't think the plural really harms value either in this case because you can be an operator running more than one fitness camp.
My 2c.