A beekeepers mask, a hula skirt, a tennis raquet and some clogs would make never want to come back.
Dudes (and dudettes). The obvious outfit is for him to go out there in a fully plated suit of armor. With a mace. You know, the large, spiked metal ball on a chain. That’d scare 'em BUT GOOD.
Okay, picture this.
Mid-Nineties. Edmonds St, Burnaby. (Not a good area!) zoogirl is walking out her front door in her usual apparal for those days - black leather hat with studs around the visor, biker jacket with LOTS of studs and a dragon on the back, boots and black jeans.
Pretty impressive, right? So, the first thing I saw was a kid, about 12, walking out of the front yard with my son’s bike. Oh-oh, not good! Wel, I let out a shreik like a banshee -"Hey! I know who you are and I’m telling your parents! - and the kid takes off like I just filled his butt with rock salt. Hehhehheh. He held onto the bike for a while, purely on reflex, I think. Last I saw of him, he was zipping down the path behind ValueVillage and he’s probably still running! 
He dropped the bike about halfway down.
It was almost as good as the time some drunk stuck his head and shoulders through our livingroom window (same house) and our shepard, King, stood up on the couch directly underneath him. I bet he’s still going too!
Go Gacy on 'em and come out in full clown regalia.
After all, what kid doesn’t love a large, screaming, psychopathic clown charging at them?
Oh, and Tripler, your situation made me think of Dr. Loomis in the first Halloween movie, when he’s staking out the Meyers house and scares the lving Hell out of the two boys who just barely gathered up enough nerve to double-dog dare each other to go up to (or into?) the house.
So make sure, no matter what you’re wearing, that you bark out something short and sharp so as to scare the canoe vandals even more.
Because, you know, you’re not really scared until the urine’s tricklin’ down your leg.
What is the world coming to?
Back in my day, teens would have set the canoe on fire, or stolen your car, or something.
I’m glad for the sake of your canoe that kids are gutless nowadays.
I like canoeing.