Better is just use GPS. You can passively listen without being tracked and you get the time and location. GPS is getting cheap enough ($10/1000 qty) to be a good option for this sort of thing.
I have a higher end GPS module. Building I'm in is corrugated steel sided with a metal roof. After being on for an hour the coordinates show... my desk. Far as I can tell.
GPS transmit power is 44db with a 13 db antenna gain. I think. And -140 db sensitivity (typical) So close to 200db of link margin. And the transmitter isn't in clutter either.
