Thanks. It seems that the best approach to this problem is to break it into three parts. Let me run through them and see if they sound right to you.
First, add the factory stock Sc2450 rear hydraulic lines and bracket to the Sc2400 and connect as though the backhoe were off. In this position, the two quick connects are connected to each other, which explains why one has extra length and merely passes through the bracket with a little extra length. With this done, verify that the control valve and the front attachment it controls are still working properly. That could be either the FEL or the front blade, which is why the manual calls it the "control valve" and not the "lift control valve."
Second is to hook up a 3 point implement that has its own internal control valve, such as a
chipper or a splitter. Verify that all works and make any needed adjustments.
Third is to decide on a placement for a rear remote and build a bracket for whatever valve one gets. It seems like a good place for this mount might be near the base of the ROPS on the right side. The hoses for this valve should probably have quick disconnects on both ends so they can be stowed when not in use. Then hook up the a 3 point implement that needs a remote valve. I've been thinking about putting a down pressure kit on my PHD for this exercise.
I would appreciate any comments as to whether this sounds like a reasonable sequence for the project, and any issues or precautionary notes that anyone sees. Thanks.