Go big or go home. Shoot for 3 inches of foam
I researched before insulating my two place. I did what the guy did and then I put the wooded walls back on with only one inch on sides and ceiling. You want three inches on the ceiling with no exposed metal showing. Metal will rob your heat and condense, drip and freeze your breath. The drips r annoying but manageable. the metal heat robbers suck and you should cover them up. I am going to put two more inches on my ceiling and put two more inches on the upper half of the walls so as not to reduce the interior width of my trailer I will also put an additional one inch on lower half of walls so they will be two inches. The floor i already started with three inches so when I went to cooke city, brought my OWN BED and slept in the parking lot it was about 50 degreess in trailer which means not enough insulation. I still saved nearly $800 in hotel fees while riding the mtns. but before i go out again i need more insulation up top and buying some HDPE plactic utility panels to put on walls and ceiling. Save money sleep in your trailer. Sorry bearclaw bob