I had a similar experience crossing the US border last month. First time got secondary questioning and told that I my GC would be taken away if I don't stay sufficient time in the US.
I am also thinking to apply for the reentry permit to give me more time to sell off my assets in Canada and relocate to the US. It's is mine intention to settle in the US not Canada. I just need more time to make the transition as a new immigrant.
Can u please share what has been your experiences so far, did u go back to the US again and were you given secondary questioning again.
Was your reentry permit approved?