We have a Club Car with an added rear seat that flips down. We had a seatbelt installed for the rear seat.
Then, we use a dog bed that is designed for use in the back seat of a car to elevate those little ones up so they can see out the car windows. It works great for the golf cart, too. But, our cart seatbelt doesn't work so we strap the seat down using other means (bungee and straps). Then, the dogs wear their harnesses, and we bought grooming nooses to clip onto their harnesses and onto the metal bar of the cart and that holds them securely in the bed.
The bed is called a Snoozer Lookout Bed. Our dogs LOVE these beds to ride in the car/cart. They also make one that is narrow & meant for the car console, but you can put it between two people on the front seat of a golf cart (if you are both slender). The beds also have a hidden drawer for storage. They are carried at one of the holistic pet food stores here in TV, but I can't remember which one. Here is a link:
http://www.snoozerpetproducts.com/pe...s-c-26_33.html