I don't know how I feel about migrating TGO to another site. On the one hand, I still feel estranged from SE, and I thought that feeling was abating, but then I followed Charlie's The Mess link and eventually arrived at a discussion of Twitterers objecting to something on the HNQ; it was depressing. So now my feeling of estrangement is back as strong as it ever was.
On the other hand, I visited Writing on the alternate site maybe two months ago, and, although promising as an early draft, it needs work. And, TGO is getting new users who are asking decent questions. What would be the plans to get them to transfer to a new site?
As for moving the content of TGO to the new site, of course we have to do that. Not to do that would be like rewriting the OED from scratch; who would read it?
I second Charlie as a moderator, and also second asking Rory and the other TGO moderators to join The Trek.
UPDATE to this answer, August 10, 2020: IF, IF we could get a critical mass of the old contributors back and active, I think the best solution is to do CPR on TGO and just ignore the parts of SE that makes us feel like upchucking. And the new contributors are mostly very good. I never paid attention to the politics and insanities on SE until the Monica Outrage, and am capable of ignoring it again, unless Monica herself could benefit from further support. Note: I haven't checked the new site recently, and I should do that.