Fence posts again (sorry)

Although I was reading the last thread on fence posts I was feeling ill and then had to go in to hospital part of the way through and so didn't really take it in.
I've a fence pack outside: 5 panels (4' high x 6' long shiplap) and 6 posts, all pressure treated. There's an existing fence to remove but the holes won't be useable due to wrong pitch. Situation is complicated by the need to contain 2 dogs, so time for concrete to set will be limited and the dogs might jump up the fence.
What were the conclusions for the best way to put in posts?
I might be able to use rapid Postcrete, or I could try to dig a hole that's a tight fit - difficult at 15" deep and 3" square. The strength will need to hold 4' panel + 6" gravel board + 2 medium-sized dogs + neighbours nattering.
--
Peter.
The gods will stay away
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30 seconds! That would be one athletic building job.
NT
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