Desert Caravan Bladder Rollers

The Desert Caravans traverse the trade routes across the Karnak Desert. They are a vital part to trade on the continent of Karnak. The caravans are made up of caravan drivers, Bladder Pushes, and Associates who support people including chefs and animal feeders, etc. 
The trade is conducted by desert caravans, usually with over 100 camels in a traditional trade caravan. They are also accompanied by up to 6 large freight rollers that traverse the desert with the camels. These rollers are inflated bladders filled with air and heavy freight items. These bladders are manhandled by people who push these bladders along with the caravans. 
The Camels and Camel Riders are the most desired position within the Caravan, however, the Bladder Rollers are equally as important but hold a much lower status. They manage the cargo that can not be placed on the back of the camels because they are too heavy or an odd shape or too long. The cargo is placed within a canvas and rubber bladder and that when closed is filled with air into a large inflatable tube. The tubes are sealed with locks and a wax seal to protect the cargo and to ensure they can not be opened on the journey.  These are very durable and are pushed by hand over the desert sands. 
The Bladders can also float and can be floated behind barges on the rivers when the caravan reaches the trade rivers at the end of their desert crossing. 
The Bladder Rollers have formed their own guild and have a very strong professional working ethis. Even though they are considered the lowest staff on the caravan, they are definitely an undervalued but vital professional within the desert trade that keeps the trading routes within the whole continent alive and working at full strength.