Hi dafydd, yes it would be ok, "BUT" when you have the caravan raised the same amount as the decking then make doubly sure that the caravan is safe and will not move at all. You most likely need extra blocks under the legs because of the extra height.
I have stayed at sites where the hard standing is actually concrete so the people who were on them pitches actually drilled into the concrete and used wall plugs in the concrete then had a wooden baton on the skirt of the awning then screwed through that into the plugs.
They were really solid and never moved because everything was at the normal height. So as I said, just make sure the caravan is secure. Have a good time.
Stewart