Yeah, I wasn't sure about your process, so I felt inclined to mention it. It is a risk without pre-dry pasteurization of the marinate/meat, so I just wanted to make sure you understood what it can lead to so you make informed decisions.
Salt, to my knowledge, won't kill bacteria like properly used cure additives, but will instead inhibit their growth until conditions begin to return to the type of environment they thrive in.
160* start-up for drying would be cause for the surface to dry very quickly, while the interior is lagging behind. If I recall, the higher temp (160*+) start for drying is an acceptable form of pasteurization, but product quality issues can result, as it seems you have been experiencing. My experiences seem to indicate that once the surface has skinned over, it really is difficult to determine the level of dryness, due to the texture of the surface being toughened-up, and higher start-up temps for drying is how this happens. I use a bend-test, along with color and shrinkage, but if the pieces have skinned over too early, it's harder to tell by texture. They may feel leathery, but if the outside is really tough, the inside can still be pretty soft. At that point, you may need to bend to the point of folding in half and see if it snaps in two or not. You probably already know this, but just in case...I've only been at the jerky scene for several years, all cured, all smoked, then dried in the smoker as well.
With cured meat, I smoke at anywhere under 100* to about 120*, then slowly increase temps after I begin to dry in the 120* range, with 160-170* max to finish them up. It may take over 12-15 hours for thick sliced, depending on humidity and ventilation of the smoker, but the R/H is typically 30-40% or less here...semi-arid. I do like to slice my whole muscle meats thicker than most, which prolongs drying time, of course, but it's the quality of the finished product that I'm really after, with the time needed to finish it being of little importance.
Some folks don't like the idea of using cure due to possible health issues, but when used correctly and eaten in moderation, there should not be any reason to be concerned, barring other health or illness factors. And for the purists, this just may be how they like to do things...I can't argue with either reason, as long as the risks and ways to avoid them are understood...then it's up to the individual to decide which route they choose to use.
Just passing info...if no cure is your thing and it works to your preference, then roll with it, but if curing could make your drying process easier or result in a better finished product with less worries, maybe give it some thought...just saying, I don't worry about mine being safe to eat, and my process yields some really nice snack food with a great chew and texture. You may have missed it, but my pepper-steak jerky (link is in my sig line) is a good example of how easy cured jerky can be, and it's thick sliced @ 3/8"...it just takes some time to dry after the smoke.
BTW, 20lbs...man, that's a nice sized jerky run! Hope all is well!