Howdy Brion -- Welcome to the Forums!
http://www.airstream.com/docs/weights-1.pdf doesn't give your trailer's load capacity (subtract dry weight from GVWR). Maybe you have a manual? Otherwise I'd guess about 1000 pounds. Be attentive to original weight and how much weight you put in with your remodel. You might get by with increasing the dry (or curb) weight by a couple hundred pounds.
Assuming it was never totaled in an insurance loss, states have their own unique ways of licensing/titling old trailers where the title might have been lost. You'll need to talk to your DMV. And yes, the VIN is ultra simple. There should be a small VIN plaque to the right of the entry door. See VIN samples at the upper left, lines 2 & 3 of
this page. Also see
http://www.airstream.com/docs/pre1980vin.pdf. You might need to print out copies of both pages to convince DMV about the VIN format.
Royce mentions searching with the Google method. See
http://www.airforums.com/forums/f138...rum-37729.html.
Specific topic areas are at
http://www.airforums.com/forums/. With this site's search function you can get better results if you use advanced search, use only one search word
and specify which subforum you wish to search.
That's not the final answer -- I haven't seen one of those yet.
Keep asking questions!