Converting from traditional aluminum siding to smooth skins?

I figured rigid foam (blue board) would be best and more then likely is what I'll go with and "expandyfoam" the joints and voids.

I've worked with the foil faced polyiso in solar heater builds for heat resistance.. I can get it locally so may go that route too.

I've got time to figure that out cause it'll be a bit before I can get it framed and skinned. Long weekend coming up.. hopefully I'll get something done.