Randy Flexner points into the backseat of his car.Theres my kitchen, Flexner said.He walks around the front, reaching inside.And heres my coffee counter, Flexner said.He pulls out a baby blue cup that says:Let the adventure begin.Flexner is in the parking lot of Florence Christian Church. Because church officials run a program that offers free showers for people experiencing homelessness.And Flexner knows it costs $18 for one at TravelCenters of…