Hitch heads and sockets are not interchangeable. I contacted equalizer and thy said smaller and larger bars are not interchangeable because the sockets they fit in are sized different, and the bars themselves are different as well. This is evident in hitch head model numbers and bar model numbers in the manual.
Your methods may vary but I sure would not do it!
Sell the 12k and get the size you want and need for your application.
2008 Toyota Tundra Crewmax Limited w/tow mirrors, 5.7L, 4.30 gears, six speed tranny, towing package, Firestone Ride Rite airbags.
2014 Rockwood Roo 233s, PI HW30-C, Equalizer 10k 4 way hitch,