5th wheel with largest tanks

It is becoming an issue that most of the new trailers are not offering things like big tanks and extra battery space for extended dry camping. We were lucky to get an Alpenlite before the company went under. It is great, and the 100/50/50/50 tanks, and a compartment for up to 6 batteries, are wonderful for extended stays. The manufacturers seem to think that the only places we go have hookups, and are for huge trailers. That is not the case, but is one of the many reasons we haven't bought a newer trailer, that and the manufacturers seeming failure to be concerned about longevity and dependability. Just a thought though, my brother bought a new trailer that had a small fresh tank and a dealer was able to retrofit a second fresh tank giving him 95 gallons of fresh capacity.