optimum canning RH is about 55%, so if your humidity is that low I would keep a close eye on those. at that RH they could dehydrate completely and that would not be good
turn the air as low as possible. it's a little better to have your out-take at the top since then you're forcing out warmer air and with an intake at the bottom you're drawing in cooler air
that's favourable because cooler temps slow the drying process
your temps are pretty good, but cooler would be better with that RH. see if you can either raise the RH or drop the temps
good luck