The “MyTools” Extension by Limitlessman has the functionality to limit slopes. So you could theoretically select all (Ctrl+A), type in your maximal slope, set your preferences in terms of which to move and click “Set Slope Max”.
Be warned though. The extension was originally written for OFS 2.0 which makes it, that there are some weird behaviors around which points are selected and manipulated, but it does work very well, once you get the hang of it.