With RV sales the past few years being out the roof and current demand still very strong, then couple that with Tiffins good reputation and also in high demand, I doubt you'll find those kinds of discounts. 30% or more on some other brands MAY possibly be found when a dealer is trying to dump a left over. Dealers don't dump Tiffins. I could be wrong—and there may be a rare bird out there—but I think you're looking for a pot of gold at the end of an imaginary rainbow. I would say for a new Tiffin 20% - 25% max is about what you're going to find. Supply and demand principals at work here.
If you want that deep of a discount, buy a gently used Tiffin about 2-3 years old.
Good luck my friend.