See if you can find out what brand and model power converter you have. Most likely replace the batteries. After that, you may have to decide if you want to spend the $ for a large solar setup or just get one of the smaller quiet inverter generators. you would be AMAZED at how quiet a 1000w Honda inverter genset is and it will run all night on about 1/2 gallon of gas. A Solar array is silent but it will not give any power at night (obviously).
I myself would just get a thicker blanket and run the heat in the morning but I understand the desire to be comfortable as one wants when camping. That is why we bring a whole house with us.
