Something that you might want to consider is to keep 3D SpaceMouse Pro just for navigation. The buttons around the mouse wheel are very useful to set up shortcuts and access menus quickly but it requires that you spend some time getting used to where they are and build that 'muscle memory’.
So there are a couple of alternatives you might want to try:
Alternative 1, is to add as many useful shortcuts as you need to the virtual shortcuts so you can access them from the same menu. For instance, you can map a 'radial' menu to a single button (like 'F' which is right under your thumb) and assign a bunch of commonly used commands in there rather than distribute them on the physical buttons. Similar to what I show in the tutorial when I cover the setup of these radial tools in my Blender setup:
The second alternative is to keep your hand over the 3DSpaceMouse Pro completely free and leave it just for navigation. This could work really well if you also have access to a Wacom tablet where you can simply map the shortcuts to a Wacom Radial menu that can be triggered from one of the buttons on your pen.
For instance, I have a custom radial menu for the masking tool in ZBrush that I can access by clicking the second button on my pen:
With this method, you don't have to rely on remembering the different settings you set up on all the buttons of your mouse but a simple click to visually see the menus on the screen and choose from there. (either from the 3DSpaceMouse Pro or the Wacom radial menus).