There are two kinds of back wired outlets; the good ones that are actually
clamps worked by the side screws, and the crap one that are just springs.
You should not be using the crap ones for any purpose; it is just not worth
using crap to save $1. You should not be using both the back and sides of
the good ones because you can't reliably pressure both.

Why not do it the right way? A pigtail is several wires held together with
a wirenut. One is line, the rest are load. In your case, you have the line
coming in, a load to your first outlet, a load to the rest of the outlets,
and a load to the switch. (Yes, you could just as easily move ONE of the
loads to the load side of your first outlet). It is no more difficult,
but is rather more reliable.