I am trying to decide the same thing. I love your MIB system and was going to recreate it with a keg. I was trying to think of the best way to do it.
Couple of options I have thought of are.
Build a wooden box say 24 x 24 and 36" tall. The box would have one horizontal shelf. If the top looked like a privy you could lower your keg into the box and then fill the rest of the void with insulation. This would also give you a horizontal wood surface to to mount a door/ cover you could close when trying to get to boil.
The bottom compartment would give you access to the pump and so forth.
The other thought I had would be to use a 55 gallon drum and do the same as above. I could just leave it in my basement and make " trash can beer ". I guess that makes option one Outhouse beer LOL.