In that day, insulation was fabric wrapped wire.These 20's and 30's homes can be interesting architecture, buy REI's aren't architecture preservationists  (baring Queen Ann and Victorians), so you've got a major GUT and restyle project IMO.

At the time of purchase I was given a rent roll for one month which I learned after closing it was totally fabricated.

If you're not replacing it for insurance reasons, you could consider having it professionally coated with a hybrid system consisting of polyurethane-modified acrylic and reinforced with fabric.

Have removed all fabrics, carpeting, etc.

Have you considered just placing pre-fabricated tiny homes out there?

Not only that, it was illegal - it is a federal crime to abuse the DMCA in the manner he abused it.So here is the point - through his "Licensed Branding LLC" team, he "fabricated" an issue of "copyright abuse" in order to try an illegal take-down under DMCA.

If you want to build, maybe don't build something on site, build it off site (pre-fabrication) and bring it on site.

If the fabric is in good condition, I may consider that instead.

There is landscape fabric under the rock. 

We used closed cell foam for the insulation and had a custom roof system fabricated out of aluminum trusses and coretin, in addition to having a porch on the south side of the container, all of which have mitigated any heat transfer.