I am always amazed at how many different brands of both 5ers and travel trailers there are each time we walk thru an RV park. Keystone has 17 different brand name 5ers and an equal number of TTs plus their toy hauler lines. Forest River has at least that many, and even more when you add their other divisions such as Coachmen, Palomino, etc. Then add in the multitude of other manufacturers such KZ, Heartland, DRV, etc. there must be a hundred different brands. And each brand has multiple floor plans.
However, when you look more closely the majority of them revolve around probably not more than a half dozen or so basic floor plans each modified a little by each manufacturer to be a little different from the competition.
Six slideouts is not that uncommon with the rigs growing in length and interior floor space. And fold out patios, both front and rear, are showing up more and more. But have not seen one yet with a front cap slideout.