What Lathanael said
You don't have to do any of that... That's what I'm trying to tell you guys.
If you look at my setup cobble goes from the Extruder to the Pulverizer, the Sand goes from the Pulverizer into the Buffer and the Buffer goes straight into the Auto Crafting Table. Once the Buffer and the Pulverizer are full of Sand (6 stacks) the Pulverizer will stop, because the Sand can't go anywhere (at that point the Buffer is full and the 2 output slots of the Pulverizer as well). If you have pipes between the Buffer and the Pulverizer this would be an issue (as items would leak out), but because there are no pipes, it isn't an issue.
That way you don't waste Sand (you're not burning, voiding or storing it or anything, just the 6 stacks in total, that's all you can and have to store) and you don't waste energy (the Pulverizer only turns on when the Buffer or Pulverizer has room for more Sand, which only happens if you yourself take Sand out or the Auto Crafting Table takes Sand out to make Bog Earth).
On a side note: I think you use RP2 tubes between the Pulverizer and the Buffer and have it work. afaik those tubes don't leak items and whatever machine you use to put the items in those tubes will stop sending those items if there is no room at the destination (in this case that would be a Buffer).
Also, as long as you take out 2 Dirt from every 6 that comes out of the Peat Bog you will never produce more Bog Earth than already is in the system. It doesn't matter how much Sand or Water Buckets you supply the crafting table, it will only do something if it gets 4 Dirt as well. As long as you allow only 4 Dirt from the Peat Bog to make more Bog Earth you can never get more Bog Earth than you started with.
I'm not sure how I can explain it anymore clearly, my setup is just as efficient as the one you've got there. The only difference is that my setup doesn't have the part where 2 Dirt every 6 get separated (or 1 every 3, it doesn't matter), but since you already realized you needed to do that I didn't bother building it in my setup (I know I need it for an actual farm though). If I add that + the Peat Bog and Turbary my system is just as efficient as the other ones on this page. No wasted energy, no wasted resources, no need for redstone logic.
I meant to remove excess dirt from the system. that is you have 1 buffer for sand, one for dirt, the one with dirt have a restriction tube going off for destruction of excess dirt once the buffers are full.
you do know that you can use a timer and actually pulse the creation of items with the help of an autarctic gate right? just set it to create 8 bog earth whenever it is time to do so.
A single peat engine should be able to power the pulverizer enough to create more than enough sand for the setup.
Oh and wait. RP2 does have a machine that set's ratios.
A sorter can pull from a buffer and paint the items a certain color. you can have it grab 4 dirt and send it to a buffer at the table, then 2 dirt and send it elsewhere for removal. it will do this for as long as there are dirt in the first buffer, but this costs a sorter and a buffer more, as well as some RP2 power, than just doing the whole overflow thing. throttling the autocrafting to slow the bog earth creating down is cheaper to do with just a timer. it might build up some excess bog earth, but once the peat farm is full, you can just void that if you want. these items were created from nothing, so you don't actually loose anything by voiding excesses in each step.