The trend towards 12V fridges has been made possible with introduction of Li batteries, especially affordable now with many Chinese brands. This takes care of one of the requirements that I wrote earlier - big battery bank.
Solar panels prices dropped significantly over the last 7 years.
Controllers TAD dropped, not much. Morningstar MPPT is still costly but less known brands like Epever and Renogy are becoming popular with 40A MPPT selling for less than $200.
Offbrand supplies like solar cable with connectors made by god-knows-who have flooded the market.
Trailer manufacturers have a lot of catching up to do, they put 12V box in but their OEM solar options are a joke, usually.
12V fridges were not too bad 10 years ago, then Danfoss improved something in control board and compressor failure rate went down. Changed the name too, it's now Secop.