Drained antifreeze after winterizing; ok or not okay?

To me, I'd rather blow out the water first, using less than 50 psi (even less if you're really worried about leaks).

Edit: looks like there's not much water in the system, if anything...

Try this: Take a half full bottle of water and pour about 1/2 cup of the antifreeze in it. Mark a line with a marker. Put it in the freezer and see if it expands.

Our RV might be further north than yours in Michigan, unless you're a yooper. :)