Sports gear, camping equipment, portable chairs, anything soft that can go on top of other luggage, all go over the side, over the back, however it's most convenient.
More importantly though, is that a lot of this gear is removed from the truck over the side, especially at the beach or on the mountain or at a trailhead, where I'm parallel-parked and can't easily remove items out of the back.
For over 20 years I have owned various models of F150 Trucks
and I access from the side more often than I use the tailgate.
Infact my current Truck is a Regular bed, and the one before it was a FlairSide ... I miss my FlairSide that is my one big disappointments in Ford that they stopped making Styleside and FlairSide Beds
I haul every day small items, and home improvement supplies, and other things like that