Great news, Still.
A few suggestions:
One - You should avoid hand-delivering petitions into mailboxes... Pinning on mailbox posts might be sufficiently non-mailboxy, but in my experience working on political campaigns, we were always admonished to NEVER place campaign material into a mailbox, as that is considered federal property and technically illegal. Therefore, anyone wanting to make trouble with you could always accuse you of improper use of federal property.
Two - If the influx of petitions start to dry up, you can always go back to the ones that came in and ask them if they can help you get five each. One could even host a kids-safety awareness "party" where you could talk to a group and get petitions signed on-site, like a political fundraiser.
Keep up the good work!
"There is a Catskill eagle in some souls that can alike dive down into the blackest gorges, and soar out of them again and become invisible in the sunny spaces... even in his lowest swoop the mountain eagle is still higher than other birds upon the plain, even though they soar." -- from Moby-Dick