They may have changed suppliers or just decided that the rear axle is to loaded up with stuff they install at the factory for towing as much weight as the lighter 24' RV?
How much weight do you plan on towing?
I know that my E-450 van can tow a lot, because it is just under 9,900 pounds ready for travel, and has a 14,050 GVWR. I can put another 2,000 pounds on the rear axle! Yet it is short like your current motorhome, at 23' long.
Adding a 300 pound hitch weight about 8' behind the rear axle, with a 158" wheelbase will take nearly 200 pounds off the front axle, and place 500 on the rear axle. So a lot depends on how much hitch weight you plan to tow, and what the wheelbase is, and what the distance is between rear axle and hitch ball. And you probably have no idea what the front and rear axle weights are on the empty Winnebago?
IT might also be that Winnebago did not get a lot of attention for it's heavier rated hitches, and they 'think' that customers are not towing a lot of weight with them? To bad that happened. .
Fred.