Dog step to 2nd row seats

As my dog is getting older, she's having trouble jumping up as high as she used to, so I decided to make a step to the 2nd row seat.

In the door area there is a plastic piece of trim at the very bottom. It is held in place by one screw, hidden under a small black panel. I removed that panel and the plastic bit that the screw normally installs into, and installed a M6 rivnut in its place. I then drilled a second hole, and installed another M6 rivnut:

Then I made this piece and bolted it down to the rivnuts:

Using angle iron, I have something to "grab" on to, which works like this:

Which is used for a large-area "step" like so::

Of course, being free-standing won't work, so I made a folding leg/support: