I too would open up the smurf tube. Check with the AHJ first though. They shouldn't have a problem if you are using approved couplings. You are limited to 360 degrees worth of bends. Total. And even that is a tough pull with THHN. I couldn't imagine pulling a fiber patch cord through all those bends. If you can't open the conduit because it's in a wall or somthing then use a lot of wire lube when you pull it. And pull Slow.
If I'm reading your post correctly, you have over 360 degrees of bends - right?
Even with pulling lubricant, it will be a struggle to pull anything through that conduit.
One thought.... If you are absolutely sure of the distance, could you cut the conduit to length, place the fiber in it beforehand (while the conduit is still more or less straight? Then protect the ends carefully since the fiber cable would be hanging out. Wrap the fiber carefully in something to protect it and attach that to the end. Then place the whole thing in place. Unwrap the protected ends and connect.
One other thought... Get some "mule tape". It's a flat ribbon of woven nylon fabric. Extrordinarily strong. Get enough for at least double the distance of the conduit. Pull the mule tape completely through the conduit (using lubricant as necessary). Only then attach the fiber to the mule tape. Now *continue* to pull the mule tape *and* attached fiber cable through the conduit. Add pulling lubricant as needed. The mule tape will be absorbing nearly all of the strain of the pull, with the fiber cable "going along for the ride" as it were.
You want a flat tape for pulling so it won't cut through of damage the fiber cable as it makes its way through the conduit. Don't even *think* about using any kind of rope or twine. It will slice through the cable at some point.
At any rate, you've got a nasty job ahead of you. I would also make sure you state to the customer that this will be a "best efforts" job and that you can't guarantee that you won't damage the patch cable. Patch cables aren't really designed to be pulled through twisting, turning conduits. Tell them that you'll give it your best shot, but no yelling if the cable breaks or is damaged by the pull.
The conduit comes with "mule tape" (or something similar) already in it. When attching the fiber to the mule tape, how does the mule tape end up absorbing the strain of the pull? Won't the attached part of the fiber be pulling the rest of the fiber through the conduit? Or do I need to attach the fiber to the mule tape at some interval?
After looking at Carlon's web site, I can't seem to find out whether the couplings can be added after the fiber has been installed. Can they?