So..... after trying the innova 5510 obd tool which states it can check transmission temp, it cannot. I returned it. I have come up with a decent idea, there is an external water to oil trans cooler on the transmission housing, the feed line to the cooler theoretically will be at current transmission temp as that is where its added on a lot of trans cooler set ups, the return will obviously be too cool to get accurate temp, I am going to cut the feed line and put in a 7/16 or "whatever size hose it is" barb tee with NPT 1/8' for temp sensor, and add an after market digital oil temp gauge, parts are under $50 " amazon" and its a good way to bypass taking it to the dealership. I am going to test this method, you could even devise a tool from the temp gauge and plumbing tee to use as a technician. However, I am not sure which models have this water to oil cooler or if its even on all the 6spd automatics, if you have a trans oil to radiator set up you can tap the feed going in there, this has to be the cheapest remedy to this fluid level issue, short of just taking it to the dealership, "as a skilled mechanic and engine enthusiast i will not go to dealership" This allows us to change our own fluid and check the level at the proper temperature according to the Toyota TSB
Update: i have confirmed with several other mechanical technicians and my Toyota dealer technician that this method WILL do the trick, tap the feed to the cooler closest to transmission add correct size tee with 1/8 NPT for oil temp sensor and bang, problem solved. if you do not have an external water / oil cooler, usually the radiator has its own trans cooler built in and you can tap the line going in there. i will update when i install parts and compare my temp on the gauge to the tech stream temp at Toyota.