Leisure Vehicle.

This is probably not a good idea, the battery is far too small for it to be more than an emergency cooker. A better choice would be a nice quiet small generator of 2kVA or so, Honda make some nice ones. The best question is why a microwave, normal propane cookers are probably a much better bargain overall, unless you are addicted to ready meals. Do they have a fridge too, presumably gas? My friend has a (large) RV but this has 1000Ah of backup batteries and a generator (key start diesel) for proper power, its very comfortable including the aircon! Charging this battery will also be a problem, in parallel with the vehicle battery is not a good idea, both being flat is not a good problem to have, and diode split charging will need a fair bit of work and an unusual alternator to deal with the volt drop and dual sensing.

This is probably not a good idea, the battery is far too small for it to be more than an emergency cooker. A better choice would be a nice quiet small generator of 2kVA or so, Honda make some nice ones. The best question is why a microwave, normal propane cookers are probably a much better bargain overall, unless you are addicted to ready meals. Do they have a fridge too, presumably gas? My friend has a (large) RV but this has 1000Ah of backup batteries and a generator (key start diesel) for proper power, its very comfortable including the aircon! Charging this battery will also be a problem, in parallel with the vehicle battery is not a good idea, both being flat is not a good problem to have, and diode split charging will need a fair bit of work and an unusual alternator to deal with the volt drop and dual sensing.