Maybe take 'er to a boat outfitter. They may be able to give you advice on what it would take to put a convertible top on it. I'm going to try something similar, but am thinking of a fixed rollbar type of bridge rather than foldable.
Joe USMC - I have a convertible top on my CSC Friendship II. Coincidentally, today I buttoned it up and even zipped in the side curtains (1st time) to check their fit and condition. It's a pretty smart set-up - pax is fully protected. Will take close-up pics for youif you'd like. Here's a pic from last year (before I installed it).
One thing I will tell you, is on my sidecar, a Champion Escort, with the top on it, it acts like a brake. It really has a lot of wind drag and makes the bike pull real hard to the right. I have electric lean on mine and even at full lean to the left, about 6-8 degrees, it still pulls hard. I would rather not use it and I haven't had it on the sidecar for several years. Just don't ask me to sell it. Carol would kill me if I did.
Hi Joe - I only had it out for 3 rides... back in January. It handled well, fairly neutral actually. I only had it up to about 85 km/h, and put on maybe 30-50 kms, so still getting used to it. We still are having very, very untypical weather for this time of year. While we've had a few cold snaps since I last rode it, today is another one of those days when if a guy didn't mind getting a little wet and dirty (from snow & slush on sideroads) I could be out riding!
You could always do something like this. On a rainy trip up the Alaska/Canada Highway in 1992, we found a surplus army poncho...cut it down, folded it and put in snaps, then screwed in snap receptacles around the lip of the passenger compartment. We then snapped our kid in, and then put on his helmet and shield and he no longer got wet! (He didn't especially like it much (couldn't get his hands out), but we were both bigger and he had to accept it! Lol....)
Joe USMC- Do you have a pic of your sei/hitchhiker setup and can you share any info about it? Does this sidecar seem heavy enough for the sei or did you do some mods to it? I tried putting a voyager on my sei and I hate it. Been exploring the sidecar idea lately as I would like to keep it and continue to ride it.