Just like Chris said. I turn ours up a to hot for a shower, so you need less hot and more cold. It really is a amazing how much you can get out of 6 gallons. However, if you use 50 gallons at home and you go through that, you may need to look at continuous hot water heater. It heats as you go so you never run out, they work on LP gas. Some are very expensive Tim on www.thevap.com
has one and loves it but they run about $1000-1500. But I think are cheaper options out there.
My wife loves long showers and has never had a problem with the 6 gal. We did not have a shutoff on the shower head so I went to Lowes and bought parts to use a gate value and it works great. I have never run out of hot water running the water the entire shower. But mine at home are only 3-4 minutes.