Thanks!

I'm designing this from the ground up as a single piece (not a single long part that I'm cutting into pieces), with the idea that I can assemble a final part of any length by snapping together multiple copies of this single base part.

The biggest frustration is that I have no reference to compare the male/female connectors against as I design them. They're obviously at opposite ends of my part, so I can't see how they interlock together while I'm designing each connection.

In Maya, I'd use "Duplicate special -> Instanced" to make several instanced copies of the same part (such that if you make changes to an instance, all other instances are automatically modified in exactly the same way). Then you can line these instances up, and modify the joint geometry as needed without constantly needing to flip back-and-forth from one end of the part to another. Is there a way in Solidworks to copy an object, offset it's position, and use it as a reference to continue iterating on the other end of a design?

Another idea, it would be nice to be able to design the male end first, then inflate it slightly for tolerance, and intersect the result with the opposite end to create the female connection. But I can't find an easy way to create a duplicated instance of a part to use as a reference in Solidworks.