When “Mr. Bob” of Bob Drayton Inc. wasn’t providing portable toilets to Southampton and its surrounding areas in South Jersey, he and his son were building their collection of dozens of decades-old classic vehicles. Now, those vintage cars are being auctioned off in a sale that ends Sunday. When “Mr. Bob” died years ago, his son, Bob Drayton Jr., took over both the car collection and the family’s three-generations-old septic service business, Bob Drayton Inc., also known as Mr. Bob’s Portable Toilets. The younger Drayton died at age 71 in January 2020 after being diagnosed with cancer, the auc…