Unfortunately, "Owner's Manuals" as we know them today did not exist until the mid-60's. We had one of the first Airstream Owner's Manuel, for our '64 Globetrotter (which went with the trailer when we sold it). We have more "Brochure" type info with our '56 Safari. I too found several Boles Aero Sales Brochures on by Googling "Boles Aero 1959 Specification Sheet
" (you've probably already tried this...), but from my brief look at some them, they talk about them being "light" but no weights are given.
You may want to look at the Tin Can Tourist site
for additional info - but I'm not sure you're going to be successful.There are lots of Boles Aero trailer owners there - they may be able to help more.
Just curious - if it's permanently placed and not going to be taken on the road, do you still have to register it? I imagine so, or your wouldn't be trying - but just wondering.