Hi Ed,
I'm 78 years old, with similar precautions re having too big a caravan.
I also have a Hyundai i40 1.7 litre diesel which I did not want to change.
We looked around and the first question was do we want a motorhome or caravan - new or used?
We decided on a caravan because with a motor home you tend to be reliant on public transport (where available) when on site.
We eventually bought a new Caravelair Antares 335 - and that's the overall length of the caravan without the A frame. The naked caravan weighs 730 kilos, with a maximum MTPLthingy weight of 1 ton (which suits the car's power, and is soooo easy to handle.
Later, we realised that this caravan is actually at least as big as, or often bigger and roomier than your average bog standard motor home costing probably £20,000 more.
I must admit that, after towing anything up to twin axles in my younger days, it has taken me a while to minimise myself as it were to the new size.
And, of course, we have much more room on our pitches.