I guess if I was the OP it would come down to do if I believe bunch of guys on internet forum for there knowledge and engineering expertise and the knowledge of Lippert frame stress testing and design of the frame.
OR
Would I give Lippert Manufacturing a call and ask for advice since they are the ones that designed; manufacture and stress tested the frames. They also make the hitches receivers to install on their frames that it won’t cause frame damage nor void the warranty if installed by authorized dealer?
If it was me I won't tow with the OP current setup but that's me.