Fixing pebble dash behind SVP?

I have pebble dash rendering that needs repairing behind the SVP. After removing loose pebble dash, would it be possible to use "expanding foam" to fill in and then paint? Removing the SVP is not an option I want to tackle for this area and can't think of how to get behind the pipe other than with a nozzle.
Other areas I can do with 4:1 cement and then splash the pebbles on but the SVP is the main area ! Please advise me if this is possible.