Kiwi, I think I'm in the same boat as you! I've got a RDL which I sent back as well to have the seat "pulling forward" feel adjusted. One thing that has helped was removing the plastic tray as you've done, BUT also removing the back 2 rubber feet. I kept the front 2 feet in place, which puts that seat at a much better position.
In the end, you really are trying to fight the bike's "spirit". It's a sport tourer. Probably the best, most reliable bang for the buck out there. But, if you personally aren't built for that type of forward lean, it's nearly impossible to resolve. (Or, I haven't had the luck I've been trying for a couple years....)
Good luck, and let me know how it works.
2017 Yamaha FJR
1980 Kawasaki kz440
2002 Honda vt1100c2 Shadow Sabre