Yes you can add a .wim that is anywhere.
Probably best to have all the recovery folder on a different partition from the one you will be installing to
If it is a .wim , it must be added as a winpe entry.
You need to browse to the wim , then click Add Entry:
Boot.wim should boot up fine.
There will be some kind of oem restore/reinstall program in it.
That is likely to get lost - it probably won't recognize where it is.
Worth a try.
Don't worry about that for now - just see if you can get it to boot up.