Good job! And....
You've shown a "great truth" that most folks would rather not hear.....
While the type of machinery used is important in these conversions, the amount of insulation is more
Back in the 80's (might have been late 70's...) I recall a great article about keeping food cold. The author had a plywood tri and was a minimalist sort of sailor. He built an "ice box" that had something like 8" of foam around all the sides - might have been even more - and his final test involved placing a 20# block of ice inside and then measuring the loss of solid ice every day and charting its demise.
He was able to make 20# last something over a week in the tropics. Might have been days longer, but I do want to exaggerate.
The point to the exercise, in the larger world, was that before he was going to install a powered fridge and have to deal with providing enough AH per day to run it, he needed to reduce the need for it as much as possible.
He said he succeeded, and I believe him!