On a new trailer being built,I would add on both ac's.
I'm an ac tech by trade and I don't think they are any more pron to problems than ac's.
Make sure it does have the heat strip option.
I did a little research and correct they do not "defrost" so it has a low temp cutoff (some 40 others 45) but if in southern half of US most time not a problem .
If either one of my units dies then I will change it to a heatpump & strip BUT I will modify it by adding a "defrost control"