How to modify Task Sequences / Unattend.xml in MDT?

I've been struggling to say the least to figure out how to contorl different Task Sequences  WITHOUT having to change anything in the CustomSettings.ini or Bootstrap files. Im going to be rolling out MDT/WDS to a lot of clients and need a very standardized and simple approach to basically do the following:

1. Task Sequence to Deploy reference OS
2. Task Sequence to Sysprep and Capture that OS after I modify to my liking
3. Task Sequence to Deploy the final image to clients

Lets say I want to have the reference OS in a workgroup, but yet have the final image deployed to a domain. Or lets say I dont want to be prompted for a computer name during the reference OS install, but I DO want to be prompted during the final deployment. The way I know how to do taht now is by changing the CustomSettings.ini, done, next. pretty simple.

However, I'd like to control all of that customization through unattend.xml or the task sequence properties (or someway I have no idea about yet) instead of having to change the CustomSettings.ini file everytime I want to switch up what I'm doing or what TS im running.

I want to configure MDT, all TS's, and call it a day. Can anyone elaborate or give me a hand on this? I've read things on Variables and the order at which settings are applied, but now its a huge cloud. I do know that the CS.ini gets injected into the unattend.xml, but I cant seem to find all of the settings in that said unattend.xml.

I tried having a Deployment Share for each task sequence, which worked fine as I could customize the customsettings once per share and call it a day...then I import all those boot images into WDS....doesnt seem to be standard practice though, and took up some drive sapce

Thanks for reading!
Brad