In the days of the Wilds Fleet,in the 70's I often saw their van out changing batteries. Until there is a battery made or another solution outwith shore power, there will IMHO be problems with hire craft.
The reason I say this is, many folks who takeover a boat, firstly NEVER listen, or rarely do, to what the boatyard tells them at takeover, they are too keen to get away on HOLIDAY!
I have spoken to hirers in the past, after they have eventually moored up, you know the ones, we have all been there, making a pigs ear of your first attempt! They had know idea it was going to be SO DIFFERENT from being at HOME!
I am a arthritic person so heat is a must for me. So if the heating wont fire without running the engine, I will do what we have always done, light the oven on the boat, or light the rings on top of the cooker. Yes, it causes condensation, but a small price to pay for a bit of heat.
I hope I won't be reading of the first £1000 fine to the then poor soul who has to pay said fine!
Iain