Mine is mounted btw the front frame rails in front of the front cross member, directly below the radiator. I have an 1/8" thick skid plate mounted 1" in front of it (open for air flow on both sides). The bottom edge of the skid plate is even with the bottom of the cross member for clearance and angles up towards the front of the frame rails.
I can't see how anything mounted under the seat area on either side can be safe...not only from sliding off rocks, or cars : ), or having small sticks (1" or more), popping up into it when run over (I've had one go right thru the floorboards on my truck), to having them totally buried in snow (or mud for those that do mud).
I have pics from my under carraige (t-case back) of my rig packed with ice... almost 4" thick..solid enough I needed a screwdriver to pick it out because it pulled a wire off my electric fuel pump which was mounted above the rear diff on the rear cross member...