Thank you, thank you very much!
All this, as a labor on your part to post is well known to me ( I am an electric engineer).
Maybe you did not pay attention, after assembling, I am doing extra processing in volume loss and it can not be calculated ,since accurate measurements can not be made after assembly.
"....Any approach you take is going to be approximate...."
If you were living in Bulgaria, i would have made a bet train cistern with Bulgarian beer/ could be wine ,but I'm not such a person /, my way is extremely precise and simple - with minimal involvement of elementary mathematics!
If you want this is my address; [email protected]
,write me and I will give you the address of DYA in Bulgaria, there more than two years ago I explained the method.