Hi again Ann.
But sorry I cant help you there. But I would be VERY careful on what you use on the canvas.
What brand is the camper?
Ours is a Customline and they have a guide on their website blogspot on how to get mould off the canvas.http://customlinecampertrailers.blogspot.com/2011_03_01_archive.html
I have had mould on ours and just put it up in the sun and used a soft broom and wet cloth and it did the trick, but it wasn't there for long so if its been mouldy for a while it may be harder to remove. Just be really careful with what you use on the canvas as it can ruin the water proofing of the canvas.
Maybe even ringing the company that originally made the camper to see what they recommend.
Let us know how you get on Ann.