What you're wanting to do is probably a bad idea for a multitude of reasons.

Think about security, stealth, controlling pests, controlling temps, controlling humidity.

If you're going to grow outside then just grow outside somewhere stealthily. Plant your plant among other things that can disguise it.

If you want to grow inside then just grow inside where you can control all the conditions.

There is nothing stealthy about an outbuilding that has noise coming from it and some slight odor (or complete odor if you don't use a scrubber) and light coming through it at regular intervals.. Unless you own a pretty decent sized chunk of land, don't have nosy neighbors and can secure it 100%.. I would say forget about it.

That's just my opinion though.