In an effort to minimize any organic (read mold nuturing) materials, we are considering plastic as the basis for the walls. The plan is to use a material similar to the stock wall panels that we had in our Sprinter upon reciept. Some discussion in this sprinter-source post.
Possible candidates:
https://corrugatedplastics.net/4mmFlutedCorrugatedPlasticSheets.html Use described here on sprinter-source. Samples of 500lb, 400lb, and 300lb material ordered on 11/17/20. Material is subject to buckle and creasing when stressed along direction of corrogations. Also, they would not send 500lb sample after they failed to provide (in spite of having paid for it).
https://www.pennelcomonline.com/us/Penn-Elcom-FLight-Panel-77-x-52-Black-Composite-Panel---Thickness-7mm-14-M865007/m-8832.aspx This material looks promising. Confirmed on 2/5/21 that local pickup in New Jersey is available.
Based on discussions with Penn-Elcom, they recommended a material similar to above. Its ABS so quick research suggests it should be compatible with more adhesives than the HDPE panels. They also directed me to an alternative website geared towards non-consumers: www.penn-elcom.com/.
https://www.diyroadcasesstore.com/corerigid-heavy-duty-composite-sheet-black-7mm-1-4/
One concern is the ability to adhere things to the coroplast (HDPE). This post shows fabric over coroplast that used 3M90 and 3M headliner according to this post. 3M does suggest 90 will work with polyethylene.
The corrugated plastic sheet would be covered by a layer of closed cell neoprene (probably 1/8") and a fabric. One fabric to consider is marine vinyl.
Adhesive compatibility
www.MarineVinylFabric.com: How can I help you? Nathaniel Costello: I'm building some wall panels for a van conversion and would like to cover them with your product. Is there an adhesive that you recommend? The fabric would be glued to a neoprene close cell foam layer. www.MarineVinylFabric.com: Sorry for the delay I wanted to get you a good answer. Most customers have said the best adhesive is a HH66 vinyl cement. Nathaniel Costello: Great. Do you know if anyone has used 3M77 or 3M90 succesfully? www.MarineVinylFabric.com: Typically 3M offers incredible products I would read their documentation for applications and environmental uses. Nathaniel Costello: Thanks!
3M80 literally looks like it was made to bond vinyl to neoprene.
Windows
We are considering bunk windows. Lorax used Motion and have a higher bed than us, so they should be find installed at the highest possible point.