Well, then I decided that instead of running everything off of an extension cord, I might as well run electrical out to the the building since we'll have a swimming pool in the backyard in a few years and I can spend the money now and run a good-sized service that I can tap into later for the pool. In my county, if you're building a structure that has electrical, you need the whole structure permitted. But I figured since I was adding electrical to an existing structure that I'd be OK just to get the permit for the electrical.
So, I took my line diagrams and applications in, got my permit, went home, dug the trench, laid down the conduit, called in my inspection for the trench, the inspector comes out, and he asks, "is the building permitted?" I explained the sequence of events and he tells me he needs to check with the office.
Sure enough, he calls back that afternoon and says, "ya, you need the permit." Apparently I can run a panel attached to a pole right beside the observatory, but as soon as I run a permanent wire inside, the whole structure needs a permit. Doesn't matter how long the structure has been on the property. And doesn't matter if what they need to inspect is not even visible (like footings).
I then ask him if he can foresee any issues with the existing structure given I used an established design and over-engineered everything else myself. And, of course, he identifies the roll-off roof as something he has no experience with and would have the most contention with -- i.e. I need an engineering analysis done.
So, now my $100 electrical permit is going to cost another $100 for the building plus the fee of a structural engineer. And my first response from the engineer is "the design is very convoluted and how much money did I have in it for an engineering fee?" He's estimating the engineering is going to cost $1000.
At this point, I'm going to pay whatever engineering is required because I've already sunk about $15k into the construction and almost $2000 into the electrical alone.
The annoying part is that I purposely designed the building to be fairly small (it has a warming room) to accommodate the 120 sq.ft. non-permitted building requirement. Had I known running a wire inside would require the full analysis, I would have made it at least 160 sq.ft. But now it's too late to increase the size.
So, hopefully, this information will be helpful to someone else down the road.
Once it is done, I'll post pictures here.