Why use the Secret Service? He's grifted enough while in office to pay for his own detail a million times over. Let him. Better yet, give him a detail for the rest of his life ... in a federal supermax prison.
What, heelinhell, you don't have a gun in your car? Are you crazy? That's the soft underbelly of this plan. What if a miscreant pops up in the backseat? You won't be ready, will you? Keep that gun in the passenger seat at the ready. You're welcome.