Why don't you celebrate with drinks at your local and post pictures as an update?
If you are not going to use KS to communicate with your backers, then I would mention it and give links to where you will post news about the project. Instagram, twitter, website etc. Also mention where they can reach you with an email.
Make sure you mention this as well in the comments so that it is easily visible to anyone.
For backers who have not given their mailing details, we mentioned this in our latest update. Explain that you have contacted them via KS and email and make them understand that the ball is on their side now.
It's important to always reply in the comment section and I would make sure the latest comment is coming from you. This show you are responsive.
If you are planning on launching another campaign, let them know that they will be the first to hear about it and benifitiate from early bird rewards.
You could also do a live streaming to talk about the next steps with Field Company. But I'm not sure how popular the Streaming is...
Another nice thing could be to write the closing update explaining the journey you went through manufacturing it and fulfilling the perks. The pitfalls, the highs and lows. Always good food for thoughts.