do you have a pic of the PT cruiser dash? is there a bezel around where you want to mount the LCD? If there is, I'd consider making a custom mount for you if you send me the bezel and the front part of the LCD (or perhaps a headrest shroud so it would snap in if there is one for the lilliput), it would be out of fiberglass and finished in your choice of materials. I live in minnestoa so you'd have to ship it but it wouldn't be much, i could probably have it done in a week or so. let me know if your interested.
EDIT: if your dash does have a bezel installation would be a breeze- all you would have to do is snap it back on or maybe use a screw or two.