Great investigative work.
What about trimmable foam inserts like this?
I also think that spray foam would work also seeing that there are many opening for the expanding to ooze out of.
Do you think there is an opportunity to add a metal sleave in the handle to reinforce the plastic? Just think that maybe some other owners could benefit from removing the handles and putting in some reinforcement.
That sucks. I think that y'all should reach out to Lexus Brand Engagement and file a complaint. The more they here about this the better.
https://support.lexus.com/s/questions-comments
Congrats on getting your GX and welcome to the forum.
Try staring a new tread with your questions in a different category and it will likely get answered. We don't have ours yet so can't help.
Post some pics of your new GX when you get a chance.