Greetings,
Continuous means the raised foundation is contiguous on the perimeter. Sorry, got the words confused. I'm working on a steep hill side design right now, which only a portion of the footprint low enough to the ground for conventional raised.
If 3 inches is all the clearance you need I still think it feasible to investigate separating the roof structure from the top plate and lifting it up that amount (perhaps a bit more) and re-secure. Especially if you are staying in the house for 15yrs. The lift may be in better shape than the Kit and Bath at the time of resale, may add value too.
Good luck,
John McA