Hey Howard,
you could ask the Leaf blower idiot in the workshop
Besides mistaking a leaf blower for a shop vac and using the Onefinity CNC machine as a lift chair, he mounted it in this orientation (X axis horizontally). You can see in the video how he modified the parts that attach to the wall.
I think Onefinity recommends the orientation with the X axis vertically becauses it facilitates feeding tiled workpieces (workpieces larger than the workarea that are machined in portions)
If you would chose “recommended” orientation, you could protect your Y axis with an acrylic or polycarbonate sheet or a vinyl cover or bent aluminium sheet like shown here:
Vinyl cover:
Plexiglas shield:
Bent aluminium shield: