[WhyIsItGlowing]

The USPS has a bunch of highly-specific requirements that they aren't willing to change, which makes an off-the-shelf van impossible.

These are things like: giant unpainted bumpers, sliding drivers door, the rear door has to be roll-up rather than normal doors, step through from front to rear, some size requirements.

One of the alternatives which was rejected when they signed the contract for the new vans was a customised Ford Transit.

[KptMarchewa]

Might be wise to rethink those instead of trying to be unique. Haven't heard about "custom post vehicle" anywhere else in the world.