Welcome to the site Marc!
Would the gas oven have an auto self igniter thing, like push a button and it goes click click to make a spark? Just guessing.
If it doesn't come with a battery, you could install a battery in to it, and then put some Anderson Plugs connecting the van to the car for charging when you hook up and leave home. Remember to isolate the cars battery when you're at your destination so you don't end up with a flat car battery. (this is a very basic outline, you can get all kinds of second battery kits and systems for vehicles depending on your needs. I have a pretty basic isolator switch in my vehicle, cost about $60 and dsiconnects when the ignition is off, but you can spend heaps of fancy systems which may or may not be necessary)
You could also get a solar panel to charge the battery when at your distination.
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