There are many ways to get a hot water for a shower (I'm assuming that is what you meant, as heating water on the stove is super easy).
Some of the hot water systems are much simpler, thus none of the issues that others have had with an FWC built-in hot water system, i.e., fails to heat water for various reasons (just when you really want it to have hot water) and of course, the maintenance requirements.
Some of the issues reported on WTW.
And, there are more just search for them.
I use a Zodi Extreme. I like the simple hand pump or air compressor pressurization, simple to heat, either on the stove or use a 1 lb. propane bottle like on portable camping stoves, and virtually no maintenance.
There are solar heated systems which are even easier than the Zodi Extreme, one which is the common water bag, and a neat one that is a roof mounted pipe/tube, both with gravity feed/pressurization.
Some use one of the shower/toilet privacy tent/hut set-up outdoors with or without some sort of something to stand on to keep the feet from being in the mud. Or, some have adopted my method of an indoor shower using a shortened utility sink as the portable shower base, and use only the curtain part of the shower/toilet privacy tent/hut hanging from the ceiling. Very nice to shower inside in a nice warm, and clean environment (my wife loves it).
The Zodi Extreme looks like a really cool system. In a prior post I had said that I wish I had hot water. I do a lot of hot springs and all I want to do is wash the sand and at times mud off after I'm done. I use a solar bag shower but I can see many uses for the Zodi. I'm looking into buying one based on your recommendation. Thanks!!