I have a camper van in Iceland for 10 days in September. Should I travel the ring road or spend in-depth time in 3-4 different areas??
Here's my honest take: do a modified Ring Road, not the full loop at breakneck pace, but a shaped version that lets you linger where it matters most.
Either way. Ten days is the minimum, IME, for the ring road, and that is good if the weather cooperates. Early September tends to have better weather than later, but starting in September the weather can change quite drastically and you lose daylight . Plus most campsites close by the middle of the month. There are some that are open, but you would need to plan ahead and for those that are open you would want to double check that showers etc are available. That is not always the case as some stay open as far as a place to park and camp, but no amenities.
If this were my trip, I would not do the ring road and instead would do the south coast, golden circle and Snaefellsness. That way you can see things without being rushed.
We spent 8 days in Iceland and didn't go further north than Snaefellsness or further south than Iceberg Lagoon. Some of the days and driving distances were very long. I'm glad we didn't try to do the ring road and don't think it would have been relaxing to do it in 10 days. Iceland is spectacular, enjoy!
Another vote for sticking to Snaefellsness, Golden Circle and the south in that time frame. We did that in a week...starting in Reykyavik visiting the town on our arrival day and then we stayed in Borgarnes for 4 nights (perfect spot between Snaeffelsness and GC and Kirkjubaeklaustur (probably misspelling...for 3 nights). This spot was a good spot for a good transition day and then Vik and the diamond beach area. Many waterfalls and sights in between. Honestly, my favorite part about Iceland was the open road. No traffic and beauty surrounding you every mile driven. Map out your must see spots and also be spontaneous and just stop and explore things that look cool. It's a magnificent country. We were there in late May and I thought the crowds were very manageable. The biggest crowds we encountered were at Thingvellir NP. Not sure where you are starting but with having a camper and the ability to move...you may even be able to venture into the Westfjords for a few days (wish we could've!) or further east, or spend some time in Thorsmork. Enjoy!
We did a great tour with Nordic Visitor, it was the Ring Road and wonderful.