Is there any reason that you cannot just used the factory approved method of pulling the dipstick with the engine running and at operating temperature, wipe it off, restick it and check the level? I just walked out into the shop and pulled the stick on a stone cold trans that I know has the correct level in it when warmed up and the fluid level only came to the top of the plastic on the end of the stick, this makes it 1/2-3/4 of an inch short of the little notch on the steel. What the fluid level is like when it is cold is completely irrelevant, you need to know what it is doing when it is warmed up and at operating temp. So, check and adjust it by the book and do not worry about it.

Mark