The bldg design you showed is what I'm building in 24' wide x 16' depth for my does. I built a 3 sided raised shelter for my buck with floor size of one sheet of plywood; 4'x8'. My buck shares his containment area (with the shelter enclosed within it), with 2 wethers that are still under a year old. When the weather is bad, he doesn't let them inside the shelter with him and they're stuck standing outside under the eaves or with their heads and upper body stuck inside the hay feeder (it has a roof). When it was the only shelter for a spell, and all the goats were together, they ALL fit inside it standing when the weather was really bad. The lowest on the head butting order would sometimes get kicked out and stand under the eaves (or out in the rain) 
The ground area I have enclosed for the three boys is 2 cattle panels long by 2 cattle panels wide (32' x 32') and one end of 2 cattle panels, where they meet at an outside corner, were cut with bolt cutters at ~ 4' so the cut section could be used as gates. One to the outside, the other to the doe pen adjacent. The gates "latch" to each other as well as the (end of the) cattle panel fencing that continues down the way to form the doe pen. I use carabiner clips high and low to hold the gates closed, and they do a fine job. The boys DO climb up the gates and place their weight on them, but though they bend out a little, it's not enough to allow them to escape, and I can grab the panels and bend them back straight easily enough.
Once breeding season is over, I'll open the inside gate and let all of them use both sides once more. Just can't do that now with yearling does too small to have bred. The size area I have for the 3 boys is about the minimum I'd want to give them if they'll be in there for any period of time. The buck, RJ, does get to chasing the wethers around at times and they need enough room to be able to escape getting "beat up" on. Especially when a doe is in heat and RJ knows and gets all sexcited... He can't get to the does, so gets a little "worked up"... I'm not sure I'd want to keep one buck or ram in an area the size you're offering for any prolonged period of time. I'm sure it would be quite sufficient for a couple of months during breeding season, to keep him away from the girls till you want them bred. I would definitely not have more than one animal in that space though.
The ground area I have enclosed for the three boys is 2 cattle panels long by 2 cattle panels wide (32' x 32') and one end of 2 cattle panels, where they meet at an outside corner, were cut with bolt cutters at ~ 4' so the cut section could be used as gates. One to the outside, the other to the doe pen adjacent. The gates "latch" to each other as well as the (end of the) cattle panel fencing that continues down the way to form the doe pen. I use carabiner clips high and low to hold the gates closed, and they do a fine job. The boys DO climb up the gates and place their weight on them, but though they bend out a little, it's not enough to allow them to escape, and I can grab the panels and bend them back straight easily enough.
Once breeding season is over, I'll open the inside gate and let all of them use both sides once more. Just can't do that now with yearling does too small to have bred. The size area I have for the 3 boys is about the minimum I'd want to give them if they'll be in there for any period of time. The buck, RJ, does get to chasing the wethers around at times and they need enough room to be able to escape getting "beat up" on. Especially when a doe is in heat and RJ knows and gets all sexcited... He can't get to the does, so gets a little "worked up"... I'm not sure I'd want to keep one buck or ram in an area the size you're offering for any prolonged period of time. I'm sure it would be quite sufficient for a couple of months during breeding season, to keep him away from the girls till you want them bred. I would definitely not have more than one animal in that space though.
