We have the larger Splendide 2100 in our Bus. We also have a 10 gallon hot water heater. We haven't ever had a 6 gallon water heater so I can't say for sure on how it would work. But, I do know that when we do laundry we may run it continually for a few loads. After using the washer we've still had plenty of hot water left over for other tasks so I know that it doesn't require the full 10 gallons. We also run our water heater off the electric element, which is slower than propane (but the shore power is free
). I would think that a 6 gallon water heater is probably going to work OK but you won't be doing dishes at the same time as the laundry.
Also, in a worse case scenario, you could kick on the LP water heater as well and run the higher BTU output gas fired burner as well as the electric element (it is perfectly OK to do so) at the same time. You'll get a faster recovery time.
Actually, this unit will mix both hot and cold water according to it's selected cycle for water temperature. And, unlike a residential clothes dryer, it does use hot water for drying. It somehow uses the hot water to heat the outside of the drum to aid in evapoative cooling.