In the power box on my Bailey Pegasus 462 the RCD (Chinese) is exactly the same size as a Schnieder at £22 from Toolstation. However it is connected to the MCBs with fixed insulated solid copper straps which I had to replace with suitable flex.
To the OP: my problem was simple mechanical tripping - nothing to do with current and a surprisingly common fault with RCDs. However if you know anything about electrikery think about how the unit in the caravan is likely to trip. You will need to be in contact with something that is at fault and live and an earth - and what is there in a caravan that is earthed and easily accessible? The only real chance of it protecting you is if you are using something outside plugged into the caravan supply and standing (ideally in bare feet) on wet ground or grass. It will NOT protect you against a EHU connecting cable fault - that is up to the pillar, assuming it too has an RCD!