ive found them very clever and able to avoid getting caught so i do this:
over the space of about a week i put the trap down with the safety catch on and unset the treddle for a couple of days let the tree rat get used to eating the sunpat goodness.....
next i did the same with the box over.......
then i set the treddle and left the safety on so it CLICKS loudly when it goes to it i jumped out at first but soon went back....
then the same with a bit of polythene carrier bag taped over the hole (to keep cats / birds out as i dont want to catch something im not trying to kill... )
next day i just set it without the safety use a brick or tent pegs to hold the box down and got one within 1 hour of rebating
not going to post the pic here as no doubt some wont like it but with patience they work well
If your roughing it, Your doing it wrong
Lack of planning on your part doesn't make it an emergency on mine