DanT:
I've had an extensive email discussion with the president at Transport Designs, Steve Mattie, and have also "checked references" with a current owner (possibly the same one that you contacted).
Transport Designs is very flexible in meeting the customers designs and specifications. I've been very impressed with Steve's responsiveness to my questions and with his willingness to build to meet my needs -- not theirs.
At this point in my resarch process, they're definitely on the short list of viable choices for a conversion company!
If you haven't already, check out their web page at:
Transport Designs
Regards,
Alan