A lot depends on the power you plan on using. If you mainly go to sites with hookups then an electric only model will be the easiest to install. Truma do a good one. However, if you also wish gas then you will need to cut a hole in the van side for the exhaust vent. My own van has a gas/electric model. To date we have never used the gas side and only used the electric on a few occasions. We tend to use the wash up facilites on CC or C&CC sites as this makes less mess. Any other hot water required is via the electric kettle