Hi,
Usually, we have paper tissues or kleenexes in a car, not towels.
'Ledge' is not a great word here, more natural would be perhaps 'the shelf in the dash'.
You need to say 'they', not 'it' in all these examples.
Say 'clean', not 'cleaned'.
I think your versions are all too long and too repetitious. If you shorten the sentence, a lot of problems go away and it's more natural. Just say I think they're clean or else they would be in the garbage.
If you have any more questions about this, please write again, OK?
Best wishes, Clive