You can use my mod to save it as the release version. Go into the favorites menu, click MORE, then click SAVE 3 times so it says save as Powder Toy release version 71 PSv format. The save it how you normally would. It checks for new beta elements and will refuse to save if you use them, but it won't check for changes to existing elements, like the recent electronic changes. If your save uses electronics, you may have to make some changes to get it to work correctly.

In the future, hopefully Powder Toy will be able to load newer saves. With the OPS format, saves could have a tag "Compatible with" that says the oldest version that is capable of loading it without any errors.