You mentioned that you wanted "modern." Does that mean you want the modern interior styling of the later models, or just that you don't want to restore a vintage trailer?
If it's the latter, I think something like this trailer in the Classifieds
would be the sort of thing you want. It's basically what SSchanger above suggested. Like the newer FB models, they have a center bath and you get at least one set (instead of two) of panoramic windows. This is also about 1/2 the price of a (well-priced) used 25FB.
That said, the 25FB's combination of a dinette and couch along the side, plus the vista views, make it mighty nice...