It sounds like the hose has been shortened at sometime, perhaps due to a split.
I think that the hose is made of silicone tubing and not too easily sourced.
Dave
------------- Give a man a fish and he will eat for a day,
Teach a man to fish and you can get rid of him for a whole weekend.
Have you pushed the collar on the pipe up as far as it will go till it almost reaches the connection on the water inlet?
That will allow the pump to go deeper.
Also, was the caravan on wheel ramps at all?
This will gain extra height so you need to raise the barrel respectively.