Del Mar Ca,
where safety and consequential legal issues are part of the equation, stick to the manufacturer's recommendations.
When it's definitely not a safety issue, look for the 'better' way.
Slate

Have you thought about just getting a floor fountain? You can bury the base so that the water is just flowing into the ground. Looks great!

Or you can use large posts to hang the water fountain to. Below is a link to a website that has a large floor fountain that i think you could get a copper finish to or whatever you needed to match your garden.

Here is a link that might be useful: Fountain

I have seen them free standing too. Go back to the nursery and ask them about it. Am sure they'd have some recommendations. You could also do a search on "brick veneer", less weight, much safer. Mona

Happy to say as an update that I have had my 'wall fountain' standing freely in my back yard. Stable and beautiful.