We now have 2 holes, or open spaces, that we need to fill. The first one is towards the top where the holding tank was previously, and then at the base where we are going to install our Natures Head composting toilet. We made patterns for both.
For the upper
backing, we used Luan 1/8th inch board. We picked Luan because it was light, cheap, and once painted sealed. It can tolerate light splashes of water quite easily.
For the bottom flooring, we used a standard piece of 3/8th inch plywood. We will drill holes right into the flooring where the original toilets holes were drilled.