I did my 2nd rear trunnion. It was a LOT easier.
First, I drilled through 3/32. Then I drilled about 1/2" deep with a 9/64.
Then I put a 3/8" long 1/8" diameter hardened dowel pin in the hole, and another on top of that, and pressed it as far as I could. Then I tipped the 3/8" long out (the first one gets a bit stuck, thats why 2), and replaced it with a 1/2" long pin, pressed as far as I could. I changed/added different length pins as I went along. This way, I didn't have to worry much about things getting crooked under pressure. I also used a needle nose pliers to hold the pins in place. Note that this was with only 3/8" and 1/2" long pins.
After the rivets came out, I was able to poke the first dowel out with a piece of wire through the 3/32 hole.
Piece of cake!
John