It's not enough with content. Without incoming links it may take an eternity to index. Just go for the simple: some social signals and a pair of comments in high TF blogs (it doesn't matter if they are noindex). It will appear in the search results in 1 week at most.
This is something personal, but your PBN should look so good, that you should be able to add a Search Console account without hesitation (you need at 1 SC per related PBN). That way, you will be able to track much better your traffic and if you make independent clusters from your PBN (never putting two related PBN domains in the same SC account), you will be fine. Altought some paranoids may suggest that there is some relationship between access IP and all that, but I'm just confident that this is extremely complex to happen. And OTT think that if the PBN has good content, it will be sustainable regardless of the interlinking strategy.
In conclusion: plan a Search Console strategy and use it for your profit.