Hi tgil,
Sorry for the slow response....I make lots of Biltong...Technically there is a need for some heat...not to cook..but to dehydrate...using a fridge would cause the outside of the meat to harden and prevent an even drying. Some people make biltong boxes....an aerated box with a heat source...this doesn't deal with humidity. Too little humidity (per your fridge) is a problem...to much also a problem. I make mine in a purpose built curing chamber where I can control temp and humidity.
You should check out the forum biltongbox.com ...might give you some ideas.
otherwise...build a box...use a
dehydrator...or make a curing chamber (my recommendation...as once you start dry aging...you cant stop). The fridge is a risky option.
Let me know if you want to know anything else.