First, the 23 in the model number is NOT the length of the trailer. Rarely does the number reflect the RV's actual length.
The 23IKSS, 23SS and 233S all have an actual length of 24' 8".
The 19 model is actually 20' 8" long.
Don't have any idea if the 23 models are the biggest currently. Though the 23IKSS's dual slideouts are unique from all the others in opening up floorspace.
Have you looked at other brands?
A few years ago, there were much bigger hybrids, some close to 28' to 30' long.
and Zoe the Wonder Dog(R.I.P.)
'07 Roo 23SS pushing an '07 Chevy Avalanche
Equalizer WDH and Prodigy BC