I really don't think water is a huge problem. (Would not want it submerged, but a little splash should not kill it.) Read the comments, and this test was done AFTER the cell was submerged in salt water.
https://www.youtube.com/watch?v=Jz37WycW-7E
I plan to just mount mine in the stock Club Car battery box.
Now, If I had an EZGO or a Gas CC, I would just put in a splash guard to keep stuff from coming thru the bottom. If I needed a mounting plate it would be a sheet of aluminum, if not it would be a sheet of coroplast.