The Amphibian doesn't convert anything...................all it does is put a 10 amp circuit breaker between your caravan and the house 10 amp circuit, if you overload the circuit by running a HWS, Jug ,AC etc all at once instead of blowing a fuse or circuit breaker in the house the Amphibian will trip, it doesn't do anything else, its a waterproof expensive circuit breaker/fuse, you only need one if you turn too much on in van, use a bit of thought and they aren't needed...........like in your house you should have a surge protector on your fridge, TV, computer, washing machine etc in fact anything that has a circuit board this applies in your van as well, my old 2009 Tardis had one on the Setek so I assume most would have them you don't need to spend 100's of $$$ either, seperate units are better though.
I have seen people using Amphibian's in caravan parks, to protect their vans, get narky when you point out the problem but whinge about the park power when it trips as they power up the AC, what happens when you listen to sales reps.