Wow thats it ? Nobody making hot water with a 90,000 btu stove.
Thought about it on my Pocono (110K) and my Anthraking AK110. I even bought a radiator that I could strap on the front (hycoils are a waste of time, they corrode too easily) but after some preliminary testing abandoned the idea. In theory it would work but these LL stoves have great flexibility through the coal-trol and when only ticking over they would not do DHW well. Also don't forget DHW takes a lot of energy
in my opinion - forgedaboutit. If you want DHW that bad do a complete hydronic upgrade or a bucket a day type inexpensive separate stove. So unless you are supplying a laundromat the amount of money saved is not worth it.
It takes about 40,000 btu's per hour of boiler capacity to put out 1 gallon per minute of 120 degree water...that assumes the incoming water is around 50 degrees. Most coils that I've seen installed in stoves are pretty small, so even if the stoker has enough grunt to do the job, the coil usually doesn't have enough surface area to harness the heat.
If you are running the stove for heat and have some extra capacity, a coil for hot water is a great way to save on some electric during the heating season. But to run the stove just for hot water...I think you will be disappointed in the output.