A fuel tank baffle assembly is provided for installation in a fuel tank, the baffle assembly comprising a main body having a first end section, a second end section, and an intermediate section interconnecting the first and second end sections. Operably associated with the main body is at least one deployable auxiliary baffle structure. The auxiliary baffle structure is configured to be positioned in an undeployed state during installation into a fuel tank, thereby defining a first installation width of the baffle assembly. Following installation, the auxiliary baffle structure is deployed into an extended position, thereby defining an operational width for subsequent usage. The operational width is greater than the installation width.