Floor bounce

First of all I know this topic has been discussed endlessly. Second, I have experience here. We formerly owned a 2006 Nash 26X front kitchen trailer. Great trailer, built like a tank. I installed the steady fast system and it was quite solid, minimal lateral movement and stabile. Last year we bought a 2019 Rockwood 2608BS. It’s an ultra light. Same length and weight as the Nash but with a bedroom slide as well. We instantly noticed a huge difference in bounce when set up. I assumed the electric stab jacks which aren’t supposed to be cranked down very hard instead of heavy duty scissor jacks were a part of the problem. We bought Xchocks for between the wheels. No difference. I assumed the ultra light frame was the problem. So I installed a set of scissor jacks fore and aft of the axles. Better but can still feel the 24 lb dog jump off the bed when I’m sitting in the slide. Also noticed the front left of the trailer sags down after a day of so by the front corner of the slide. So I installed a 5th scissor jack next to the stab jack on that corner. I still have an incredible amount of floor bounce. I’ve given up and assumed it’s the fault of the ultra light chassis and design. I don’t think the steadyfast system would help because it’s not lateral sway, it’s vertical bounce, unlike in our Nash. Any ideas before I give up?