Seems to me that everyone here is obsessing over a logo approach that tries to solve the issue when the real problem is
a) Does the business have good established branding? AKA "What Would Dan Antonelli Do"
b) Sell the concept with the wrap design itself, once branding is established
He'd probably be amused at the weirdness of the business concept, but happy to quote them on the branding and vehicle wrap design. Soon after that, they'd be amused at the quote, thinking it was ridiculously high. Shortly thereafter, he'd be laughing, although simultaneously saddened, to see how they've probably wasted their money on a horrible design, and how they surely spent tens of thousands of dollars on a truck, design, yet thought spending a few grand to market it properly was a dumb idea.
And he'd see yet another poor small business owner hamstring their success by placing no value on their marketing of their business.
This is all just speculation of course, and has no basis in reality.