I think your predictions, and Lon's are pretty well spot on. Its unlikely the technology for this market niche will be ready for 10 years or so and as you say the capital cost is high and the mileage is low.
It maybe that biofuels or sustainable fuels will serve this market - they will command a price premium as they are 50% more costly to produce at the moment. The% bio/sustainable content is regular fuel is only 5% rising to 10% at the moment to count as sustainable -this was designed to encourages uptake while keep the price down. The % of bio/sustainable content will have to rise to 100% at some point and that will add to the cost.
From a save the planet perspective, getting passenger cars to EV quickly is the priority, as its addresses 50% of the problem and can be rolled out quickly. As EVs become universal then charging points will become universal. HGVs are next on the list. I suspect caravans will be further down the list. The Dutch do a lot of caravanning and don't have an indigenous car maker any more (DAF taken over), so they may well get something going in the is area as they have a lot of battery R&D in Eindhoven.
This is a very active development space. I've got clients making very low internal resistance batteries for server farm back-up supply and for fast charge points. The cells, trickle charge all day and night, but can be discharged very quickly when a vehicle plugs in. They are designed to even out the load at the substations.
National grid has a huge expansion programme unfolding to provide connectivity to distributed generation and supply, but this is a 20 year plan.
New technologies such as solid state batteries which offer lighter weight, higher power density, greater safety (ie no flammable solvents) are being developed - still some way off being commercialised. So at some point the caravans and motor homes challenge will get addressed, but it does feel like it will be further down the pipeline.