Tongue weight issue on new toy hauler

Hi all, new to forums, first post. Just recently picked up a 2019 Wildwood FSX 280RT. Purchased the weight distribution hitch and had all installed from dealer. I am towing the unit with a 3/4 pickup. When I towed the unit home dry I had no problems however that all changed once I loaded the toy into the back. I have a Can am Maverick X3 with a dry weight of roughly 1700 lbs. Once I hit the highway around 55 mph and attempted a lane change, the unit swayed terribly causing me to cross all 3 lanes and almost lose it. I took the trailer and truck to a cat scale and got 3 weights. Truck, truck and trailer dry and truck and loaded trailer. I then took the unit to have it looked at by a local individual who advised the tongue weight was way under what it needed to be. The problem we found was that the toy hauler garage is 136” and the rear axle sits at 127”. This means that when you put a toy in the garage, nearly all the weight falls behind the rear axle removing a good portion of tongue weight. With all the info I contacted Forest River who came and picked up the unit and took it back to Indiana for testing. That is currently where we stand. I will say that Forest River has been quick and in constant communication throughout this process. My question is, has anyone ever experienced anything like this and what can I expect?