I have been looking at the electric teppanyaki style table top griddles but am still in two minds about getting one for the caravan. One thing to look out for is the wattage. Some of them use 2000 watts or more which would be fine on most uk site where the norm seems to be 16 amp electric hookups but we spend a lot of our caravanning time in France and over there, the sites we use tend to be a maximum of 10 amps and a 2000 watt grill would put us close to the limit. I have seen a few 1500 watt ones which would probably be more suitable for taking to campsites.
We've got a large round Quest table top grill which is low wattage at 1300 watts but they also make rectangular ones without a lid that operates at 1400 watts.