Larry_Loo

Oilspot,
If I understand your plan, you intend to attach wood blocks underneath the flange of your plastic battery box so that the weight of the battery will be transferred through this built-up wooden flange to the top of your trailer's floor. You also plan to place a rectangular, 1/8" sheet - with a rectangular cut-out area into which the battery box will fit - on top of the floor so that the battery's weight will be distributed over a larger area than that of your wooden flange. Is this correct? If this is what you intend to do, then it should work well. I would not, however, recommend that you attach the 1/8" sheet and wooden flange with bolts penetrating through the entire floor. Not only would these through-bolts increase the likelihood of road moisture seeping through the floor but also you increase the risk of electrolytic corrosion of the bottom aluminum sheet when moisture gets between the bolts and aluminum. A more practical solution might be to make the rectangular cut-out in your 1/8" sheet sufficiently snug so that the battery box will not have much wiggle room inside the cut-out. Then glue the 1/8" sheet down to the floor with a coating of construction adhesive. This is the all-purpose adhesive (available at all hardware stores) that comes in tubes and bonds masonry, wood, metal and most plastics. After hardening it will be more than strong enough to hold your 1/8" sheet from moving around while your TM is bouncing around on the roads. You can apply small dabs of this adhesive or a continuous bead of silicone caulking between the bottom of your wooden flange and the 1/8" sheet to assure that your battery box will not move. If, for some reason, you later need to remove the battery box, you can slip a knife's edge underneath the wooden flange to pry it up off the 1/8" sheet.
;D ;D