cheap way to insulate a mobile home with strawbale and reused polystyrene?

hi everyone, this is just an idea i have for a cheap, quick and not so pretty way to insulate a 28' x 10' mobile home. I will place unplastered strawbale outside on dampproof footings, probably gravel filled tyres, on the 2 coldest walls up to roof level. Then 75mm (3") reused polystyrene in 8' x 4' slabs on the roof (so it will take approx. 8 slabs). The roof is sealed already so I will simply fit a sheet of plastic over the polstyrene to keep it dry and place it out over the top of the strawbale it keep it dry too. Then to secure plastic, polystyrene and strawbale simple tie it all down with rope. Strawbale slowly deteriorates over the winter and is replaced next summer. The old bales can be used as mulch or left in the compost. Im not sure if its worth it. Any ideas?

Too many fire hazards.

William may be right if you are in an area prone to wildfires. Landscape maintenance can make a big difference and perhaps a single light stucco coat or scrap sheet metal for protection? I think it would make for a very affordable and permaculture-like building envelope that would perform really well with the right air sealing verification and mechanical ventilation for fresh air.

I watched a dumpster full of polystyrene go up in flames at a place I worked at years ago. While I fully understand your idea and applaud your thinking outside the box for an inexpensive insulating material, I'd be scared to death of the idea of having that stuff wrapped around my house. It burns WAY to easily and acts as it's own fuel source.

Maybe strawbale treated with a diy Borox fireproofing?