Not sure what the ATS has to do with cold nights, unless maybe you were using generator to power a space heater and starting/stopping it periodically. And you could move the genset wires to the other terminals on the faulty ATS so that it doesn't have to switch to use the generator.
In any case, something must be damaging the ATS to have multiple failures like that. Water? Dirt? Broken wire connections? You can try a different brand (see twinboat's reply), but if something external is causing damage that may not solve the problem.
Alternatives include TRC/Surgeguard 40100, Progressive Dynamics PD52V, Go-Power TS-50, etc. Maybe cheaper than Parallax too.
Former owner of 2004 American Tradition and several other RVs
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC