I don't know if this is interchangable with the spider?? but it might be an option. http://www.unlimitedengineering.com/slipper.shtml It may also need locking to handle the torque of your monster (drill some screws into it). Then you don't have to mess with the spider.
I have tried that slipper on my Cen genesis brushless conversion and I had a hard time stopping the slipper from slipping too much and melting. When I locked the slipper with red loctite I snapped the rear output on my first run. The units meant to slip the metal isn't up to the task if locked
Really! Interesting to know. If that's the case then anything else you use is likely to have issues as well. Maybe best to leave it spool out to ease the pressure on the drivetrain.