Reminds me of the time I was wishing our minister happy birthday and asked him how old he was going to be. He told me 58 and groaned. I told him, 58 wasn't bad, I was turning 50 myself that year. 58 officially was still middle aged. He shook his head and asked me "How many 116 year olds do you know that are still alive?" Pretty much ended the conversation.
I've heated water on the stove for our tub back in Illinois more than once. Our water pressure sucked coming from our hot water heater. By the time you got it filled it was cooling off. I'll do the same thing here when we get a tub installed. Easy over the winter months. Just set big kettles on the stove and let the wood heat do the work.