please try this first
I did exactly what you did last season, (adding viper shocks, )and had the exact same issue.
I thought...what have I done !!!!!!!....
so. 10 miles down the trail, I moved the rear shock's front attachment ( bolt mounts to a curved slot) closer to the pivot axis, this gave the shock less leverarm at this attachment, effectively reducing the shock rate...
this allowed the suspension to settle more once i sat on it, and therefore moved the center of gravity lower, and MADE THE SLED CORNER ON RAILS AGAIN !!!!!!
amazing what effect that ride height has on turning handling.
i weigh 180 lbs and have not had the suspension bottom out to my knowledge.
this also gave me the best ( softest) ride considering all the discussions on viper shocks being too stiff.
I am extremely happy with the setup
I just hope that going to a new track with different studs this year doesn't screw it up
also, I have 10mm gaps on either side of the transfer rods when i sit on the sled
hope this helps
Ramb