2001 Dodge Durango Thermostat vs water pump vs alternator

I was driving from 7,000 foot elevation to 5,000 foot elevation around 650 miles, towing small trailer 2000lbs. I have a 5.9 liter 360 engine. On the last 50 miles my suv began overheating and the charging alternator reading on dash was negative. My lights began to go dim. I pulled over at a gas station and looked at the cooling system as there was radiator fluid and water all over the inside of the hood and engine. I refilled the radiator with water and the reservior for radiator fluid with new radiator fluid. This calmed things down for about 20 miles. Overheating began again, so I turned on the heater inside the cab. It worked, leading me to believe it was not the water pump. I also could see fluid flowing through the pipes with the cap off pretty fast. My only suspision is it is the thermostat stuck open. There was not any obvious area where the fluid was spraying from. I have lower and upper hoses, new thermostat, new radiator fluid to change out and will do this today. The serpentine belt is new about 10K miles. The alternator is functioning and charging the battery. I have refilled the fluid s again and still have a leak somewhere. Radiator looks ok. Anything you might recomend or confirm what I am doing?

Thanks much,

Jeff