We don't have one but have met people who use these freezers and all have reported good results. However, they are usually on shore power or generator rather than depending on battery power.
The Engel is a compressor-type freezer, so it should be very capable in hot weather. The downside is the power draw, as Carl says. It is 3.1 amps in freeze mode and on a hot day it could end up running quite bit each hour, especially if the lid is opened periodically to get out food, ice, etc.
You didn't mention how many batteries the trailer would have, or what size batteries, but it is pretty typical for a trailer to be equipped with only one Group (size) 24 battery. Larger trailers may have two. Each Group 24 deep cycle is rated to provide 85 amp-hours, but in practice you get only about half of that before the voltage goes so low as to be unusable for anything other than [dim] lighting. Therefore you figure 40-45 usable amp-hours per battery. Dividing 3.1 into 45 yields 14-15 hours. Since the Engel's cooling unit probably does not run continuously except under extremely hot conditions, it will probably last at least twice that long or about 30 hours and possiblly even 40 or so, assuming no other loads on the battery (unlikely). Doubling the number of batteries [to two) essentially doubles the time, which should get you through a weekend of camping with moderate electrical use.
Note that while on shore power, the trailer's converter/charger will provide 12V power and there is no battery drain.