Finally got to the place where I could put the battery tray in. I first used a air punch and placed holes around the lip about every two inches. Taped up the area where I would be welding, primered it up and undercoated the bottom of it with 3M Rubberized Undercoating.
It did take a little persuasion to get it in to place, but I actually had it in place within 30 minutes or so. Had to use a few screwdrivers to shoehorn it in to place. Went on and tack welded it in place and now I need to go around and put in a few strategicly placed welds for a more permanent hold.
Next will be to pick some seam sealer, fill the seams and start to replace the outside skin I had to remove to get the tray in place.
Below are a few pics: