Hi, Do you have the oven out of the trailer ? If you do, the thermostat is probably stamped in ink someplace with a part number. It is most likely made by Harper Wyman or Robertshaw. I'm not sure where they placed the plate with the model info, on the ovens. Maybe its on the backside ?
Are you sure it is the thermostat that is bad ? The reason I ask is there are other components that are linked to the thermostat that also fail. For example, the safety valve on my old oven was bad. 90$ for a used one, 150$+ for a new one that has to be modified to fit the older ovens. I also had to replace my thermostat, it cost 45$ used. I'm not even sure if I could get a new one.
In anycase the oven is goin to have to be taken apart to some degree to repair.
Do you use the oven much ? If you do, you might consider getting a new one or holding out for a good used one.
Maybe someone that has worked on a wall oven will chime in here. I just worked on the one in my range.