Not sure how long ago u guys took the course, But having just taken it back in sept i was impressed.. the instructor was super helpful going into great detail on how to's for setting them.. main rule 6-8 loop and 6 off the ground for fox and 8-10 loop and 8 off the ground for yotes... by no means am i a expert, being my first year trapping..
with that being said i can say for fox i would stay with a 6" loop.. I had a 7" and got the only one i got so far.. but found 7 being to big i got him in the back hip..