I think your method of loading a semi with one hand is too complex, at least for an emergency, though it may be safer for range use.
I have seen it done like this: Take gun in hand, place it in waistband.* Pick up magazine and insert in gun. Remove gun from waistband, bump gun butt on hip to be sure magazine is seated. Drag gun (as you described) on pants leg to retract the slide and load the chamber**. No need for two magazines or an empty magazine.
*Other options are in the off-arm pit (if there is enough arm) or between the knees.
** With a 1911 type with normal recoil spring guide, the slide can be pushed against any handy object, like the heel of a shoe or a table to retract the slide and load the chamber.