I have not heard of those brands, but used a Webasto brand coolant and also a bunk air heater for 14 yrs in my own trucks. They perform as advertised and give lots of heat although on diesel fuel. Not sure what your intended fuel source would be in a trailer. Your propane furnace will be your best choice from an economic standpoint. Webasto and Espar are the big players in the heater market for trucks, offshore copies are unknown quality and performance.
2009 GMC 2500 Duramax
2014 cruiser 35SS