It may not be wise to count on it. It surely is worth a shot to keep the mirror suspended as it might help.
Accidental reflection may be seen. By a strange coincindence I recently watched an episode of "SAS - Survival Secrets". A quote from that was "a guy with a wrist watch can compromomise the entire mission". Those blokes do not want to be found. So for our purposes a tuna can sized watch may help to be found too.
The incident also shows how good those resquers are.