I have always done th same as what you are doing, I generally need to tweak the density a little as I go to bottle, but not much. Sometimes I need to thin it, sometimes I need to thin it. I do either in either the finisher or the water jacketed bottler. I've most often done 15 gal batches, at times I needed to add up to 2 qts of distilled water, other times I needed to evaporate off aqt or 2. I now have a 30 gal barrel aging so the numbers will likely reflect the bigger size barrel.
Dave Klish, I recently bought a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.