Ref Noise, I think it may be down to different models and maybe different compressors?
I had a Waeco CRX-50 in my T5 and I didn't so much hear that coming on in the early morning but FEEL it as the judder the compressor made transmitted through the cabinet and onto the cupboards that made up the bed base when starting up. Once running, no noise.
The current 240V Fridge in my LT I really cannot tell when it is on or not or when it starts up either. I actually open the door if I want to know to see if the light is on (Compressor running) or the light just flashes every few seconds (compressor off).
It is that quiet (and yes, quieter then the Fridge/Freezer in the kitchen in the house).
Fantastic everyone, thanks v. much. I was aware we may need to add another leisure battery, and the wiring needs sorting anyway, so was planning to go for 8mm cable. Lots more to think about re. a solar panel, as know nothing about them yet, but sounds as though it may be essential. Various discussion about inverters - presumably this is so you can use a domestic fridge to reduce the cost, and if so are there any downsides?
A basic 100W Solar Panel in the Summer will easily in one day put back in a battery what a Compressor Fridge takes out over 24 hours
A basic 100W Solar Panel in the Winter is primarily an ornament.
Domestic Fridge in a campervan? you need to add a door lock usually; you need to tape down shelves and maybe use baskets to keep the produce from shifting around (they are not expected to go round corners when in a kitchen); They are also not designed to go in a moving vehicle so you take your own risk on that with the moving, bumping and shifting (I've had no issues with my own one).
You need to get a decent sized inverter (far bigger than the fridge needs when running) in order to cope with the in-rush current.
This is my own take on the subject -
https://www.wildebus.com/blog/products/selecting-the-right-inverter-for-an-ac-fridge/
Overall, an AC Fridge + Inverter is still a fair bit cheaper than a 12V DC Fridge