Bank Shot by Donald E. Westlake

Instead of robbing a bank, Dortmunder tries to steal the whole building

Encyclopedias are heavy, and John Dortmunder is sick of carrying them. While in between jobs, the persistent heist-planner is working an encyclopedia-selling scam that’s about to blow up in his face. The cops are on their way when his friend Kelp pulls up in a stolen Oldsmobile, offering a quick escape from the law and a job that’s too insane to turn down.

Kelp’s nephew is an FBI washout who’s addicted to old-time pulp novels and adventure stories. He tried being a cop, and now he wants to be a robber. His target: a Main Street bank that has temporarily relocated to a large mobile home. Breaking in is impossible—there are seven guards and a police station down the street—but mobile homes were meant to be driven. Dortmunder just has to drive the bank away.