I don't KNOW the answer, but I suspect the answer is NO.  Self-service is easy enough for someone to pick up at Atikokan, Nym or French Lake (even Prairie Portage has that option).  But, if someone has to cross the lake to take care of a drop box, my guess is that "it isn't happening."

Any any case, if you have to call the park office, please post what you find out because I may be following in your tracks next season.

dd