To start with - probably not worth it financially. And if you would want to do so nevertheless, wait for yours to fail first
It all depends on how much the slamming is bothering you really. I also think there is quite some difference between the individual cars, so yours may indeed be harsher than other people’s….
There are two rotateable “bump-stops” on the tail gate… I wonder if they can be used to regulate the closing in any way?