Dale's comment inspired me to share our story -
I gave up the idea of doing it myself but had the opportunity to watch two others try on our 47 sedan, one an earnest mechanic and one a car glass installer who was recommended by a local restoration shop.
The mechanic's unsuccessful attempt was with string. The string kept breaking and cutting the rubber. I suspect he was using the wrong kind of string but the other problem for both attempts was that it seemed like the glass and rubber was all just too big. On the advice of the mechanic we took the windshields back to where they were first cut (templates were made from originals) and asked if they could shave down the edges. They may have tried, but I didn't notice much of a difference. In truth, I didn't realize at the time how delicate and time consuming that could be so the glass cutter was likely very conservative.
The next and successful attempt was by the car glass installer using Dale's method. He used a hook (like a cotter pin removal tool). I don't remember a spoon, but he may have had some other device I can't recall. On a towel at a side workbench he set both panes of glass in the rubber, leaving a space in between for the center rubber and trim. The two panes and surrounding rubber were then placed on the car as a unit. I wish I could remember his route around the window, but I recall the top was last before he installed the center rubber and trim piece. And of course he had those suction cups. I helped a little in holding the glass, but with the tools he had he didn't need me much.
He was at it a long time and to be fair we still have several marks in the rubber where the hook was being used (no holes or tears, but small lines). It all seemed a VERY tight fit.
His suggestion to me for next time is to order a slightly thinner grade of glass. I don't recall the code for it. I just hope I don't have to do this again any time soon (ever, really).
Addendum (Found some notes I scribbled when glass guy came):