I think that's probably the best thing you can do for that fridge to give it a fighting chance at getting the glycol cold enough. A dorm sized freezer would work better (something like this
https://m.lowes.com/pd/Hotpoint-3-6...RmpFDnH6A4loRvhizpu-6mjYj0Nm4kQxoCQ5UQAvD_BwE).
The benefit to Glycol is that it has a freezing point at -74 degrees Fahrenheit, WAY lower than a freezer can get down to. So the colder you can get the Glycol, the more efficiently it will cool whatever system you're working with, and the fewer the chances for the reservoir heating up due to recirculation.
Sorry if any of this is old news to you.
I've been putting my eye toward doing a project like this, which is why I got so excited when I saw Anvil had a chilling solution. Sounds like you're going to make a significant improvement on their idea though!
Thanks For all you do!
Pete T