Why have expensive and complicated electrical systems in your van that can cost well over $5,000? If you are going to run a microwave, blender, hot plate, coffe maker, or anything to do with heat you will need a lot of power. Your batteries will have to be located within 3 feet ideally of your inverter that converts 12v to 110v power. This also complicates space and layout issues inside the van. If you have a lap top; a simple pure sine wave inverter will do the trick and plug into a 12v outlet. Keeping things 12v keeps costs way down, simplifies the build greatly, and keeps things really simple. Adding an inverter and extra outlets isn't much different than adding a panel to the side of your house, that's not cheap is it? A 12v auxiliary battery and solar can be under 4k, add a large inverter to this easy can add another 2-6k depending on what you want, location, and outlet options.
Solar is recommended when using fridges or parking for extended periods of time while camping keeping your aux batteries charged up because you are not driving
Larger Deepcell AGM aux battery increases ability to run larger items and go longer without recharging. Here is example of stock battery on right and upgraded battery on left. 2 x more available power.
Example of a simple inverter that will plug into a 12v outlet. Make sure you always use Pure Sine Wave Inverter for your electronics.