I apologize for misplacing this thread. It was my first post and my brain was melting from frustration. I should have scanned the forum more closely, but I saw something about .obj files and assumed that was what I was looking for.
Thank you so much for your help! I hadn't even noticed that you could extract meshes using MorphMaker. This has been extremely useful. I've been playing with Blender and MorphMaker this morning and I pretty much got the sculpt I wanted. I might try my had at making a preset from scratch since I've gotten the gist of how to make a decent looking body from looking at other peoples' edits and mimicking them.
Out of curiosity, is there any way to extract the presets found in the base game in order to use them for my own purposes?
As for applying a texture in Blender, I was referring to what is shown in
this video, starting at around 1:18. The artist puts a game texture over the model so it looks like what the head would look like in game. I don't intend to pack a texture in with the mesh, I just think it would be helpful to see what the body would look like fully rendered so that I can better match up the planes of my edit to the details of the skin. Honestly at this point it's not really a big deal since I've been able to get a decent idea of what areas I need to modify by going back and forth between Blender and TS4 and checking to see what works. I've already gotten a good result using this method, so seeing the texture isn't essential, it's just that it might speed things up a little.
Either way, thank you again for the info! I really appreciate it. You filled in the missing puzzle piece I needed. My sim is already looking quite snazzy.