Springy works well. The one tip i'd advise is not to "double click" on the files you need to edit. Control-click and select "edit with" and the application. Double-clicking seems to not recognize the save correctly after you've made edits.
The script i use is from here:
https://www.mobileread.com/forums/sho...ip+epub+script
Works great, but if you are working on a mac, be aware of the invisible files it will produce. They often create errors when epubchecking.