The year after Hurrican Ian destroyed out dock, I purchased the floating dock that you see in the photo.  But I have never used it.  However it has been outside, leaning against the wall under outdoor stairs, so it is dirty.  But the pump and instructions have been stored indoors.  You will need a pickup truck and someone to help you transport it.  It is 8 feet by 5 feet and 6 inches thick.  

From the amazon page:

Solstice Inflatable Floating Dock for Lake & Ocean, Supports 4-6 People

8 X 5 Ft, 6 In Dropstitch Swim Raft, Nonslip Deck For Adults, Kids And Dogs, Also Useful For Boat Detailing, Bag + Pump

$349.99