Just as an update, I did a lot of research and ended up using a diluted concentration of muriatic acid to clean the trailer. At the Menards where I shop, the product is called Sunny Green. You can find it in the paint section. You can also find the acid at pool stores, as the acid is used to lower the pH in pools.
Make sure you dilute it, as you want to weaken the strength to give it time to work as well as to prevent damage to the trailer. Also, the acid will eat at cement, so if/when you drip onto your garage floor or driveway, be sure to wash it off with the hose.
Thanks for the tip on Speedy Clean!