A friend of mine that also makes biltong a lot, uses Safari biltong seasoning but adds liquid garlic and liquid chilli for flavour and heat. He adds it to the fluid that drains from the strips of meat.
Both of us turn the strips every 45 minutes, 5 times and tip the fuids on top every time.
I like his biltong, real garlicky and a nice kick to it.
Both these products can be bought from food shop specialist.
Regards,
Jan.