We finished the retractable slat section for the couch and part of the bed and tested it before fixing it to the base/storage. It works fine so now will screw it to the base and will be ready to take it to the van when required.
The slat is made using 42mm x 19 mm all-dressed pine. The base using Tasmanian oak timber and plywood treated with clear varnish.
Freetasman 