Hummm, I guess I must be lucky,lol,,I live on a farm and the house is 110 yrs old, so not sure about insulation, but I do see spikes of 101 and lows of 97 but in any event I had a 100 percent hatch first time, I just didnt realy spend a lot of time, watching the thermometer and let it go...
I recently purchased a LG and was my first time using it and got a 100 percent hatch, all hatching on the 21th day. I dont understand the bad rap, I had very good luck with it. I think some peolpe just stress on the couple degree variations but I just set it for 100 F and kept the humidity...
Well, if it was me, I would wet some paper towels and put them in so that the humidity would come up, as you say you have no way to measure humidity,,,,just my 2 cents...