It’s not just the weight of the water…it’s the fact that it’s SHIFTING weight.
The size of that rig is far bigger than I originally thought and a V-6 at altitude in the mountains is likely to really struggle towing that thing.
It’s almost a ton empty and by the time trailer and vehicle are loaded with all of the incidentals and passengers it’s anybody’s guess as to what the total gross weight will be.
I’d consider a V-8 gas or diesel rig and install an aftermarket transmission fluid cooler along with considering boarding the dogs in a kennel. While I’m not saying this would apply to your dogs, not everyone is enamored with barking or meddlesome dogs, and so on.
Some vehicles will get worse mileage with a V6 than a V8, especially when towing. It’s better to have more towing capacity than less.