On the subject of lining the interior...
The fire engine I drive at work has Line-X brand liner sprayed on all the interior surfaces. We like it very much for day in-day out usage. The texture is not rubbery at all. It seems to be wearing very well too. As for sound deadening, I cannot speak intelligently about that. It's a fire truck after all and we wear noise control intercom headsets due to the sirens.
Sorry about the low quality pictures, I snapped them with my eye phone.
