Keel coolers should really be mounted as close to the centre of the boat as possible to allow for maximum submersion time and to be as low in the water as possible. When we took up the floor it looked like quite a piece of work, so we decided to ‘test’ the cooler by using the sea water rinse fitting in the galley which we never use.
The cooler is quite simple to fit, as with all ‘holes’ in the hull under the water line there is more preparation in making sure everything fits, is clean and very well sealed. You must not antifoul the cooler either. Just the earth to run to the negative of the battery its done.