Personally, I'm leary of the permanence of the plastic overhead assist handle, even if it is
screwed into a receiver attached to the roof. I think the plastic handle in the rear seat of a
car is well suited for holding the weight of hanging clothing… but not more.
Fortunately, there is a small piece of equipment that is designed to use the strong attachment
points of the door latch, the Stander HandyBar. It has a great whacking hunk of metal that
runs through the handle and is integral with the latch hook... you could use it as a small hammer!
I've known two older folks who used and swore by these bars. They especially liked that when
temporary mounted for use they were low down where they could really push down hard to
either raise themselves from the seat, or ease them selves into the seat, which you can't do
with the overhead handle. Note that you can both push and pull on the bar, It even clips to
the seat belt for storage and easy access.
In some cases, the Stander swivel cushion can make entry and exit much easier too:
Both these items are on eBay and all over the Inter-web.
NB: I have no financial interest in these products.
The two older folks are my late Mum and Dad.