TB, that dark Bramah is REALLY handsome and enviable.
Guineas are not my favorite. They chase everyone else away at feeding time and they just won't shut up.
I think KFS only has the 2x4 wire, but it's really heavy gauge and wide. 2x4 will keep adult birds in and dogs and cats out but not the mongoose. Hardware cloth is a little easier to find, but it's too expensive for this pensioner
We have a small 3'x6'x3' experimental pen with just plastic mesh housing a few sacrificial left-over quail for bait.. It is on legs a couple of feet off the ground. The mongoose is supposed to be able to climb a little bit, but I've never seen him actually do it. Maybe he will not go to the trouble.... the evil thing. If that doesn't work then we'll try hanging pens from the monkey pod trees.
I bought a roll of 1x2 wire, 2'x50' on Amazon last year. It was cheaper than the big box stores and free shipping with Prime. The damn roll weighted 65 pounds! How can they possibly mail something like that across the ocean for free? But, I promised our favorite mail carrier to never do it again after watching her struggle to push and drag the roll from the street up to the house on security camera play-back.