USHOG… you are deifinitely an experienced gardener as much of what you doing is right on and as you know lowering soil pH is a much tougher task than raising it…
There are basically 2 approaches: Biological and Non-Biological.
Biologicals can be done 100% organic, but require a lot of material and are temperature sensitive. This is why it is not uncommon in Central America for entire crops of legumes to be planted and tilled under annually and grazing cattle to be moved into a field every few years. Luckily the temp issue isn't a concern in these tropical climates. As for trying to achieve the same at the home garden level in the US, you would want to make certain you have a nice sandy substrate soil below 12" and you can utilize composted pine needles or imo, peat moss is better. You are going to need ALOT of it and this approach will take time and will work better in the South due to the overall higher temps, which keep the biologicals cooking. You could also opt for elemental sulphur (s) and while some suggest ammonia based nitrogens, I do not, as this approach will require you to use way too much to achieve the desired ph at the detriment of other levels.
In the Non-Biological category you have aluminum sulfate and iron sulfate. These are not temperature sensitive, faster acting and will help to move the soil pH much lower, but need to be applied sparingly and over time as they can drop pH significantly if over applied.
So if you need to drop the pH by 1 point or more, I would recommend utilizing aluminum sulfate and then trying to maintain with organics. If up north, then you might be forced to always incorporate some aluminum or iron sulfate.
Hope this helps,
STS
ps: Smoqman: The simple answer to your question is there are plenty of organic approaches to Tobacco home gardening and to make it simple, typically what is good for tomatoes is good for tobacco, this simple rule of thumb alone can allow you to grow a nice home plot of sweet leaf.
pps: You know what is weird about this conversation is my wife is a Master Gardener in the State of New Hampshire and gives lectures all across the state on various gardening related topics, but I am not a gardener, my experience is from commercial tobacco cropping and my interactions with tobacco farmers. So we rarely talk about anything like this, I think she would be stunned to read my comments in this thread… lol