@simsurace
The Markins PN-Z7 does not fit your description, i.e. it does not cover the entire bottom of the camera and thus does not act as a grip extension. IMHO the vertical part is also poorly executed, the thinned leg makes it flexible. Both the RRS and the Smallrig are much better, in this respect, rock solid.
For the times you can live without the vertical part (eg handheld shooting) and want a very good grip extension, the Meike MK-Z7G is worth a look. Excellent grip, but a little weird looking. It has a horizontal dovetail.