I've got a Hiace and have a 120w which I would say is minimum. I also have a 220w which is a little heavy. These are folding but I would and will have them installed on roof next vehicle. The 120 w runs my fridge and lights and charges phones etc. The thin bendable ones are coming down in price and might be worth considering as well.
Horses for courses depending on what you want to power with the battery.
Excuse my ignorance but what would an 80w panel run? I have a similar vehicle and so much to learn.
The reason for the small 80W solar is space and the idea about putting it out as soon as one is stopped is to run a 40ltr Engel or Weaco until dark. This then runs these fridges until they cycle then charges the battery. The battery should have been nearly fully charged when the vehicle stops. As the firdges use approx 3 amps when running and the panels can generate up to approx 5 amps then there is some room for charging when the fridge is going.
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I was tired yesterday and I'm tired today betcha I'm retired tomorrow. he he.
For a small vehicle like yours I would suggest an 80watt foldup panel. IE. 2x40watt jobs. Small and easily stored. 
