We have a 20 year old freezer and fridge system, engine driven compressor with salt (plus ???) water eutectic in the cold plate

One freezer cold plate has a leak on a weld at the bottom corner. Refer to photo
We have two cold plates, approx. 1 ft x 1 ft x 3 inches in the freezer, so the system works with one empty, but of course does not hold the temperature so long.

Plates are 316 SS sheet about 1/16" thick, welded. Made by Fleming in Calfornia about 1995.

Best answer is of course a new cold plate, but we are in Madeira, cruising towards the Caribbean, so finding a fabricator is not easy, so I want to try a temporary fix.

We can hand sand the leaky part to remove loose corrosion. We will not try for about 10 days, since we first have to eat the contents of the freezer, then thaw it out

Suggestions on best way to seal the leak would be welcome
We have Sikaflex 291i on board, and my current idea is to clean the bad area, apply a thick layer of Sikaflex then force it upwards against the leak with a wooden wedge.

We have epoxy on board too, and could perhaps buy a magic potion if anyone know of one that beats Sikaflex 291i

What liquid mix to put into plate. Salt and water only?