Turns out the spring goes back in without major issue.
If anyone does the rear ball joints, do not buy the ebay tool, only buy the Pelican Parts or Turner or ECS rear ball joint press or BMW etc. They are over $130 but worth it, I spend 3 days truing to get the ebay one to work and it only worked after I broke a bearing and realized I needed to file down the flat spot inside edge to fit the wheel hub. Just buy the right tool. I lucklily could swap the bearings to it finally worked but barely.
Don't use this one
https://www.ebay.com/itm/401839111915