Power split device ATF level measurement device: ideas?

Having lost a Saturn due to not having a transmission fluid dipstick, I would strongly like to have a convenient way to check the level of ATF in the Prius power-split transmission.
Jacking it up until it's level and then removing the 6-bolts and 12-clip under cladding took me a good hour, so I really want a better method.
Suggestion: Take a solid threaded plug that fits the transmission fill hole (I bought mine from "Mike") , then drill 2 small holes to insert two insulated wires with exposed bare ends about 1 centimeter apart inside the transmission. Run the two insulated wires up to the top of the engine bay where you can easily attach a volt-ohm meter. When the car is parked slanted slightly to the passenger side, the level of the ATF(which would be at the lower edge of the fill plug when the car is level) ought to cover the exposed ends of the wires and result in a notice able decrease from infinite ohm resistance. If you slant the car over and do NOT get a decrease in resistance, that is the sign to get the level of ATF checked and adjusted .
I realize that we have to calibrate this system to the exact level of slant required for a definitive reading, but I would be a lot more likely to do this check on a monthly basis than I am to ever roll it up on ramps, level the car, and remove the bleeding splash shield to check the ATF level .
But does anyone have better ideas?
(Moderator: not sure I have right forum, so please shift as necessary.)

 

Transmissions I've worked on previously have all had vents of some type, so think I would be ok on pressure. Temps get high but RTV sealant rated for transmissions ought to be good for temp and exposure to ATF over long periods.
BUT, if no one has had tranny failure due to low fluid in a Gen 3 Prius, then it is truly a non-problem and I would be wasting my time. I just didn't like the looks of those metal crush washers when I finished changing the ATF on our Prius last week. With all the under cladding to absorb a slow leak, I am no absolutely sure I would notice it in time and hence the desire to have an objective indicator.
Will check if ATF would have a non-infinite resistance reading as this method depends on that.
The alternative of designing an ATF fluid level dipstick seems to me to involve even more complex fabrication and difficult installation.

 

Nuts! Toyota ATF is truly dielectric and I measures the same infinite-ohm resistance in the new ATF as I did at the same 2 centimeter distance in open air. Therefore, the two wire probes idea will not work.

Other ideas?
E.g. Pressure- actuated Micro-switch on inside of fill plug with leads thru it to outside? I am leery of the danger of anything mounted on the plug coming loose and getting smashed to bits in the planetary gear system.

E.g. Visual check using glass/lucite prism set in middle of plug that changes reflectance when submerged in ATF versus when inside tip is in air. I would connect a lucite tube to the outside and run it up to top of engine compartment for an easy visual check from the top.

Constructing and installing a fluid level dipstick would just take a heckuva lot of work as the spaces are tight in the engine/transmission compartment.