If you do it Nathan, please make sure it’s done professionally and not like your stick on van decal.
Your van advertisement looks awful with the pictures on it. (Being honest)
But this idea may be a good one, you’ll never know till you try it.
I remember some mates of mine who set up a stand at a car boot sale, with signs etc, to sign up new customers. I remember thinking, hmm, fair play, probably beats canvassing.
The result was amazing, they signed up loads of customers. Now yes, I’m not sure how many would have stayed regular, but that’s the same with any form of canvassing.
So go for it, but just make sure it looks professional and not got your mobile phone pictures of you cleaning a conservatory on it! Your van graphic just screams amateur!