Often I see only sheet rock above them.

First of all, the venue rocked.

But PS, I have a terrible arm and can't toss the rock.

@Chad Rocke thanks for the shout out!

You are going to have to spray foam it to keep it from sweating inside and you are still going to need to have studs even if only a 2x2 to have somewhere to hang rock. 

I lived there myself for 4 years, then moved out and converted it to a super-profitable short-term rental (it's ideally situated near great restaurants/nightlife, the National Zoo, Rock Creek Park, and hotels that host professional conferences).

In those cases, making it easier to evict someone doesn't prevent them from putting rocks or cement in your toilet.

Quote from @Chad Rocke: @Daniel WatsonCongrats on the job and love the idea of house hacking.

- rock, concrete, asphalt, Security $10,000, Electric/lighting $8,000; Other $10,000;  This is in the countryside so no engineering cost.Below is a layout.

You could probably find a nice 10 unit apt building in Kalihi or Waianae for cheap but you'll need to hire security.There are whole lot new project anticipating moving into that direction, such as building higher/stronger seawall.Folks that visited regularly notice would notice there would be much more lava big rock stone allocated in front of the beach.