There's a big difference in the frames alone. You can't just beef up a frame without some really serious modifications which would void the warranty anyway. Outdoors RV has their own in-house built heavy duty frame in a class of it's own and it shows in their substantially higher CCCs. If it's more CCC you want, you need to find a brand and model that has it.
The Spree Escape will be a bare bones, no-nonsense TT. The Outdoors RV ones have many standard features that the Spree Escape won't
Each brand you mention is in a very different category.
If it's more features in a KZ you want, why not look at the Spree line (their top of the line model) like the 240BHS plus you'll get a 2 year warranty instead of 1.
When shopping for a new TT, don't go by the factory listed CCC or other dry weights. The CCC will be less and the TT heavier. Sometimes the numbers change little, sometimes a lot.