OK what's the Secret ?
 

There must be some secret to cleaning the rear (plastic) window

I guess I'm told old ,too fat ,too tall to clean the inside of this window
Gave it a go today after muscle cramps in arms , Charlie horse leg and a sore back I went to other areas easier to get at :p

I wiped it off with damp paper towels and could see it was pretty dirty Plast x will have to wait for another day. Or maybe a small double jointed detailer

Must be a wand / stick with an attachment to hold cloth allowing easy access

There are wand/stick things available at Griot's Garage, Autogeek, other detailing places and Amazon. Use something with a soft fabric though, don't use paper towels which may scratch the plastic. I have a glass window, but to get to the inside of it, sometimes I partially lower the top so I can kneel on the seat facing the back of the car to clean the inside of the rear window.

PlastX will do the job. I think I had the best luck moving the seats all the way forward, then releasing them forward. Then you kinda have to jump in there. Or pay someone else to do it.

I had seats up and tilted forward. At 6'1" & 215 I felt like an elephant in a shoe box

Need some yoga classes for next attempt

Read owners manual how to put top in service position (to access top of engine).

Once you've unclipped the cloth covering at the back, you can fold up the back half of the top a bit and reach underneath.