Insulating this rig is a huge job, I looked into the cost of a 600 board ft kit of spray on foam, which would be enough to do the job. That kit cost $575.00 and then you figure the time and materials to prep the areas you didn't want insulation to get and the cost would be about $600.00-$700.00. I got a price from a local insulation company for $1400.00.
So I decided to save some cash and do what others have done. I figure I'll save just in materials $300.00 vs Foam. Like I said "Huge Job..." I put reflectix down against all exterior sheet metal. I used the best adhesive I could find to secure the reflectix to the sheet metal. I could not get to some areas, so I bought cans of Great Stuff and foamed them. There are some areas I did not want to foam, like near lights and wire connections. I'll have to figure something out in those spots
Next, I cut to fit R-15 faced insulation and put them everywhere I could get to. This along with the Reflectix was a pain in the rear because of all the custom cutting and fitting. The foil tape worked great and one large roll did entire project. There are some spots that did not get insulation, areas in between pillars with no access holes, just get everything you can short of cutting metal to get to an area.