I have finally done it. After using ClassicPress for my personal site for a long time, I moved my business site https://hinterlandspress.com/ to ClassicPress.
I use the SiteOrigin pagebuilder and pro widget plugins on the site. Talking (email) with Andrew at SiteOrigin, they are passively supporting ClassicPress in that they "aren’t testing with ClassicPress " but promise to help me with any CP issues which come up. In fact after using their tools for years, I have had no issues and don’t expect any.