I've just plumped for an Anker Solix 800 Plus with camping lights and a solar panel. It should easily run the
Halfords fridge for 3 days when we are off grid. We've managed 3 days in summer with ice blocks with it - just. It will also power the battery charger should I ever leave stuff on in the van, but from what I can see, it powers down all the lights after a few minutes.