WoodSolutions Technical Design Guide #04, Building with Timber in Bushfire-prone Areas, is currently under review. However, a 'generic' tiled roof system (ie. one not restricted to particular brand-name products)  is included in Appendix H of Australian Standard 3959:2018. We will send you an extract from Appendix H under separate cover.

We weren't sure if you were looking for suppliers of cross-laminated timber, or design professionals. Suppliers are well represented on the net and you will find them if you write "Australian CLT suppliers" or similar in your browser. Details of local CLT projects are also available on the net such as Forté Living in Melbourne, more info here: https://builtoffsite.com.au/emag/issue-04/forte-living-australias-first-multiresidential-clt-building/.

There are many building inspectors on the net who offer a professional service. In heritage matters we have had good reports about Richard Forrester, formerly an inspector with the NSW Forestry Commission. You can access his website via this link https://paragonengineering.com.au/team-member/richard-forrester/, phone 7227 7775, mobile 0429 646 112.

We assume the alfresco ceiling won't be exposed to the weather in any way. All species of timber react to gaining or losing moisture by swelling or shrinking. If the timber is in a stable environment, tongued and grooved lining boards are available in a number of Australian species from companies such as Austim. You could also consider V-joint plywood or 'engineered' flooring, depending on the appearance you are looking for. Engineered flooring generally comes pre-coated which could be an advantage when installing a ceiling.

It's unlikely that significant deterioration would have occurred after 3 months' exposure to moisture, but clearly the leaks need to be fixed and the timber allowed to dry out. We assume the floor is made from a grade of plywood with a moisture-resistant adhesive. A business that can test your caravan is Southern Independent Building Inspections. Their usual business is inspecting buildings but they have assured us they can moisture test your caravan. Phone 0400 292 226, or visit their website via this link https://sibi.net.au/.