This is not foam board insulation as you are considering & as others have recommended. However, just as a thought you might want to consider the "Blown In Blanket System" (BIBS). Frankly, I don't know if it has an application for your trailer, but for thermal & sound insulation it might be hard to beat. I've had (5) home, my last being the largest, but having the BIBS system & I can honestly say that this type of insulation is the best I've ever experienced. I can truly say that with this BIBS insulation it costs less to heat our home than previous, smaller homes.
As I understand the technology, it's composed of shredded fiberglass that is blown through a large hose & is combined with an adhesive based vapor system. It not only is an excellent insulator, it sticks well to every nook & cranny & around plumbing for a complete, thorough application. There are no breezy door/window casings, outlets, or other wall penetrations to contend with later. A durable netting is stapled to the wall framing to contain the blown fiberglass and is then covered with the sheet rock.
Like I noted, this may not have an application for your particular needs, but if you have thin exterior walls it just might work well. If interested
http://www.certainteed.com/products/insulation/fiber-glass-insulation/317369, & other info sources are readily available.
Good luck with your trailer.