I use my RV fridge but I do not get that much insulin, plus the fast acting (At this time) is vials and syringe instead of pen (Long acting is pen) (Used to be the other way around)
There are several "Toy" fridges that have basically no moving parts (Other than a fan) I used to use one of those for some things (not insulin) but I call those a "-30 box" they cool to 30 degrees BELOW room temp. (I could design one for colder but the cost would be excessive) They also draw a lot of power for the amount of cool. The one you'd need drew over six amps. I did ship a smaller one to a friend who used it in her care between home and hotel when traveling (engine running that's not a lot of power)
If you go with a portable.. NORCOLD I think, and possibly Dometic, and for sure Engel (I'm sitting next to an Engel which I use as a Freezer) make compressor driven units that are VERY good at converting 12vdc into COLD. They are a tad pricey but they work very very well.. Mine goes to zero and draws... 3 amps running.