The Iceland Camping Essentials
Cash - Here in Iceland every shop, every gas station, every campsite, every grandmother knitting a wool sweater, has a credit card machine. It's stressful to travel around with lots of cash and in Iceland you don't have to. Memorise your pin and keep minimum amounts of cash with you in case of emergency.
Alcohol - In Iceland, the government runs the alcohol distribution (no we are not part of N-Korea). This means that you can't buy beer anywhere. There are state-run alcohol stores in all "major" towns but their opening hours are limited, plus they can be hard to find as alcohol advertising is strictly forbidden. Buy more than you think you need and always refill when you can.
Food - Buy or rent a cooler. Most camper van rentals offer coolers. Otherwise, you can find them at large grocery stores in bigger towns. The cooler will save you money and time if you fill it with essentials. I recommend you buy local food as you travel; it's fresh, it is environmentally friendly and it supports the smaller towns which you'll be travelling through. You'll find typical hot dog/hamburger/pizza gas stations every 50km. But most of them taste like garbage and cost an arm and a leg.
How to keep clean while camping in Iceland
Showers - When travelling with a tent in Iceland, you can can camp anywhere on untilled land for one night at a time (you can sleep on farmland or cropland as well, but only with permission from the landowner). This is fantastic in terms of the intimacy you will get with nature, but after some days, you'll start to smell like old socks. Thankfully, however, there are swimming pools with showers all over the country which you can use to refresh.
Here in Iceland, we have a lot of geothermal energy which allows us to pump boiling water out of the earth at low cost. This allows for an abundance of pools, which now serve as our cultural meeting points. This is where Icelanders gather to discuss current matters, relax, and enjoy themselves. Bring a swimsuit and go swimming daily.
Almost all campsites also have shower facilities. These will serve you better if you are travelling with a campervan, tent trailer or collapsable camper, as you must retire at a campsite each night; it is illegal to camp anywhere else if travelling in one of these.
Washing clothes - At campsites you will find washing machines that you can rent for small amounts of Icelandic króna (our local currency - not traded internationally).