I haven’t tried, but there are tools for attaching to an existing skeleton, I think? But I’m not sure that would suit what you’re trying to do, exactly.
This isn’t far from what we were doing on Felix years ago. We had the same guide and base topology as a template for each character. When you build, the skeleton is the same, and importing the identical skinning is just a matter of importing the skinCluster (or even the template guides) with Python. So I’m not sure I would constrain myself to having a template that was permanently built, as long as you have that template info stored.
But if you still want to, the skinning management might be tricky as you add custom joints for each character. Is this for games or film? If it’s for film, maybe the new’ish multiple skinClusters feature would help you layer on a separate skinCluster for the clothes and accessories, without modifying the base skin.
zooTools Hive has this great feature where you make a custom group that gets constrained to your existing skeleton. And as you go back and forth from guides to finished rig, that constraint remains, so you can parent custom stuff underneath. So that’s a clever way to attach things to the rig. (And you could do something similar if your skeleton is permanent. But you might have to reconstrain parts of the built rig with post scripts.)
Also there was something I did on Felix for certain post scripts, using defaultDict in Python. Which lets you define a default return value, but if you feed it custom info it will override it. So you could base your post scripts on that, where it only grabs new info as you create it. If it’s missing, it just grabs the template stuff.
You could also try serializing some easy-to-read, and easy-to-edit list of connections you want to make between built rig and skeleton. Some text notation like:
parentConstrain, spine_05_jnt, coatButton_ctl
connection, arm_11_jnt, sleeve_ctl, tx
Or something. But is that any easier than just scripting it, when you start hitting new exceptions and features? I don’t know. I know our script repos got pretty messy! 