Did a search but came up with nothing, maybe the way I wrote it. Got some old diesel fuel in my MH. Last time we used it was 2015. Some time after that I put about 20 gals in it and now it has about ...
The key with diesel and any other fuel is to keep it from accumulating moisture from the tank "breathing". To do that, when parked for any length of time keep the tank full. The smaller the air space at the top of the tank the better. In your case, 2015 diesel is fine. In AZ moisture is not a problem either. Do carry an extra fuel filter in case you need to change it and then when you return fill the tank up and park it.