Looks like you've been hijacked.
From LPI website;
Cl;icky link **Note: Please refer to hitch manufacturer’s
instructions regarding the compatibility
with the Lippert Turning Point Pin Box.
Not all hitches are designed to accept a
wedge block that relocates the pivot point.**
Now on page 4 and 5 in the clicky shows the different wedge blocks required for different hitch brands. The slot in a 5th wheel hitch top plate isn't the same exact width so ya' gotta' have the correct wedge plates to for every thing to work right.
Looks like you have some leg work checking with each hitch mfg for their input.
Lots of you tubes on the turning point pin box system. Most I saw were using a PullRite conventional hitch with 4 in the bed pucks for the rails or std rails.
Check out some you tubes.
Which brand hitch for the turning point pin box system ??? Pick 3-4 hitch brands you like and contact each hitch maker for their recommendations.