I've got a webasto compressor fridge and a 35 year old Electrolux 3 way, I have to say that 35 years has moved technology on quite a few light years. Not that the Electrolux has not been good, I'm not oversure the Webasto will be still be running in 35 years though.
The webasto cools and freezes and has performed well in close to 40C just recently in the Australian Summer. The Electrolux does struggle in high temps and you cant open and close the door a dozen times and expect it to remain cold.
The webasto runs off a
solar panel and a couple of 100aH house batteries and has never run the batteries flat. Its been running for the last 2.5 years apart from a couple of defrosts.
Solar panels are a must if you want to park up for a week, whereas the 3 way can run off gas and will only draw a small amount of current to the thermostat.
As with all things refrigerator the installation is critical, especially airflow and venting. Read the appropriate fitting instructions for whatever fridge you buy and make sure that the cabinet wall thickness is correct - 1/4" ply will not do the job no matter what a salesperson tells you. 1" minimum and better still if its made from 25mm cool room panel.
Try and get a "tropical rating" which has better inbuilt insulation.