Not really.
The defroster lines you can avoid by getting the lens right up against the glass, i do that in my little 5 door hatchback mounting rear camera off metal frame on hatch.
Not quite sure how close to the glass different mounting options let you go, but if you have the lines in the footage its just a aesthetic thing.
The sliding window i assume you can get around in 2 ways.
1: mount off the glass wit the wire coming from the same side the glass slide to, this way when open you have some wires dangling but when closes it should be tight
2: mount off the headliner or other features back there, my rear camera are off the rear hatch and using a neodynoum magnet as spacer and "mount" so easy to move around / take off.
And due to the shape of my rear hatch it let me slide the camera to within a mm of the glass so i dont have defroster lines in the frame.
Tint of course block some of the light, but in all cameras you can tweak the EV setting for that camera to compensate.
Some brands also offer a waterproof rear camera unit, that way you could place the camera all the way out back, but then you have to keep the lens clean as a good deal of crud accumulate back there ( at least on the truck i owned back in the day )
A camera in the back cabin glass will also have a lot of the bed in the frame, this could be good if you use parking mode and someone take something from the bed of your car.
But otherwise it do make plate capture ( which you should not focus super much on ) a bit problematic as directly behind you you can not see the plate on the car there, and further back you start to get near the distance where it is also impossible to do due to the nature of the wide angle lenses on dashcams.
In perfect conditions you can only read a place from 4-5 car lengths from the camera, so if we say your bed is 1 car, and the "shade" behind the truck another car length then you just have 2-3 car lengths left of sweet spot.
And due to the American license plates design/size you can probably scratch one more car length just to be on the safe side.
BUT ! plate capture is just a thing if you experience a hit and run, in which case you should see the plate and call it out for the microphone to record, this would also be a very good idea if you do that at night as dashcams cant really do plates at night as no one drive at crawl speed.