I think its a good idea but i doubt i will ever see myself using one.
I try to only do around 2-4 fields at any one time on each farm and once the field/s are cleared i will move on to the next ones, this way, using say 30 traps or so per field, i dont have too many traps set in one area as i have had plenty stolen and losing too many can seriously harm your wealth!
Simpy writing how many per field on a piece of paper, and using bamboo markers for the traps is just fine for me , but i applaud your ingenuity.