I really appreciate the convenience of my Efoy. Not only does it not disturb me it looks after itself. I just leave it on standby monitoring the battery and it cuts in automatically if the battery gets low. I can leave it in standby all winter when the mh is in storage. A generator would be cheaper but it has to be set up/started and probably should not be left unattended. It does away with the need for a second battery, takes up about the same space and weighs a lot less. It works for me but it is not a global panacea.
Okta, if you isolate you batteries, any decent ones, be they lead or lithium, should survive several months during winter storage with acceptable self discharge.
Put them away fully charged, isolate, then come back in the Spring, all should be good. Otherwise you might have a dud, which needed replacing anyway. Charge them up again and set off with confidence.
Really I do think some over-think and perhaps are tempted to put in far more stuff than they actually need. I don't need much 'leccy, a modest amount of solar (not the entire van roofed with panels) in the Summer is all, but the generator is essential in the winter, when I use more power, if not moving on every day.
LiPO4 batteries have many advantages, much lighter weight, more usable capacity, fast charge acceptance etc. Even durability if you believe the numbers. If starting again I'd consider one. Perhaps lithium might be almost a lifetime investment. Whereas lead is a consumable, prepare to replace them as and when, as you do your tyres and brake pads, it's just a running cost. Look after them well and they can give great service.
I don't obsess over power anxiety, the basic display gives me a clue, if worried I know how to use a multimeter to be more precise. If I fitted a Lithium I'd want to have a decent monitor for it, more expense and complexity. In any case I have a pretty good idea of what my simple installation uses and what I have is more than adequate, particularly if moving on every few days.
I still carry the generator in the Summer, if only to power the Remoska to cook up something that I couldn't do on the gas hob. No I do not have a huge inverter either. Coffee makers, microwaves, electric kettles, hairdryers etc. No I don't have nor want these sorts of things. Nor a bunch of IT that steadily sucks power. Just a couple of mobiles, tablets, a laptop and a rarely-used telly.
My generator only cost me £80 from ebay. Used once, put away for several years, wouldn't start, sold for spares or repair. Took me an hour to take it entirely to bits to satisfy my curiosity (they are very well made), clean the carburettor, then use. I was previously very skeptical about generators, but now I wouldn't be without one.
Everyone has different requirements, and many options are available. What suits me may be completely different for others. Thankfully many options are now available.