Hi Sandra,
I don't have any experience as an owner hiring their van out but I do as a hirer who hired one.
Before we committed to purchasing the panda we thought we should hire a van and take it away somewhere to make sure we liked caravanning before outlaying the $$$ on a new van.
We looked at a number of commercial places but couldn't get anything as it was quite close to Christmas.
I came across
http://www.privatecaravanhire.com.au which is a site set up to let private owners hire out their vans as you are looking at doing.
I went through and found one that was suitable and available for our trip.
I contacted the owner via the site, filled in a questionnaire about our trip and arrange to meet him and look at the van.
He checked out my vehicle to make sure I have electric brakes and to see that I had a license and had some idea on how to tow something and we agreed that I'd hire the van.
He had a proforma contract that we both signed, and I checked and he had appropriate insurance to protect both of us.
I used the van for 3 weeks at a pretty reasonable rate, and the whole experience was really positive from both sides.
Now I have my own van, I'm not sure if I would be able to hire it out the same way.
I'd always be concerned about how people were using it, but I guess if everything is properly insured, and you vet the people appropriately then it could be an option.