I would advise against welding a screw or other object  to the end of the
rod.  Sometimes it breaks at the weld joint and the wire is unretrievable.

Better solution.

Pot in a brass coller in the front of the hinge area which allows the rod to
thread through from the front  corner of the air intake.  Replace the set
screw with
a pretty set screw and you can access that screw just on the outside edge of
the cowl air intake hole. I countersunk the screw base so the screw head is
flush with the outside cowling edge. Also bend the forward edge of the rod
about 150 degrees or so so that when you push the rod into the hinge there
is a rounded edge on the end of the rod.  It looks like a V and the tail is
about 1 1/4 inches long and is faired very close to the inside lip of the
air intake. This can be easily grasped with a small 4 inch channel lock
pliers and pulled out of the hinge. Use the channel locks to install the
wire rod by pushing 6 inches of wire per stroke.  There is nothing more
painful than threading a stainless steel wire through the palm of your hand.

I have seen a ball bearing welded to the end of a rod but that too is
subject to failure.

Bob Smiley
N94RJ