Except for this part, sounds fine. I'm not parsing what you are trying to say here.
In general, new config allows you to assign any drive to any logical slot, and drives assigned to parity slots will be totally overwritten, drives assigned to data slots will mount and be usable if they are recognized as having a valid formatted partition. Unrecognized drives in data slots will have the option to format them, regardless of content. Sometimes previously valid drives will not be recognized until you manually set the desired format type in the disk slot settings.
So bottom line, as long as you don't put a drive with data you want to keep in a parity slot, you should be fine. No need to rebuild the removed drive if you don't need the data in that slot.