Hi All, I am just completing a home-built camper of similar construction. I used many tubes of Sikaflex 252 adhesive to attach China made "E Panels". The panels are made with a 3 mil plastic solid core with aluminum bonded to both sides, painted at the factory, white. I sourced the (substrate) E Panels from Montroy Sign Products in Reno/ Sparks, Nevada. I used the panels inside and outside with aluminum trim. I like the look and the panels should hold up well. They cost about $50. each (4' x 8'). For the roof and the front I used a similar product with a 1/2" plywood core for added strength. I found this substrate at Montroy also. This product was easy to work with and I was able to cut it like wood- I used a fine tooth blade with my circ. saw.