proof of concept vetting?

I have a concept that I am hoping to build proof for... but am looking for someone with experience to vet it:

Outdoor, unplugged, year-round, aquaponics in Missoula, MT.

In a 16x16 greenhouse bury a 2x6 round steel stock tank in the ground
Line said greenhouse with standard greenhouse insulation + bubblewrap
Surround this sucker (stock tank) with a rocket mass heater
Build and place an 8x8 platform thingie that has a 2ft perimeter of raised beds filled w/ clay media with a 4x4 plexiglass cover in the middle of it (for feeding and harvesting of the fish)
Install standard flood and drain rig
Run the pump via car battery
Compost goat manure in the corner
Feed composted (or fresh?) goat manure to the fishies
Grow nitrogen loving veggies
Eat fish.
Eat veggies.

I'm hoping that the greenhouse setup + cold frame sort of thing + composting + rocket mass would be enough to keep this puppy warmish in my zone. Thinking to stock perch or trout, despite tilapia being the most widely cited species in aquaponics (at least as far as the internet is concerned) . Perch and trout do well in our nearby rivers and lakes.

Is a steel stock tank not the ideal material for keeping things warm/cool?
Is 16x16 too many cubes to heat?
Should the manure be composted in a spinny thing or should I just keep it piled up and exposed?
Are there any CHEAP greenhouse tips?
OK to feed fresh goat manure to fishies? Compost it first? Put some duckweed in between the two?

Thanks so much nice people!

Beware of galvanized steel tanks, they may be toxic to fish: http://practicalaquaponics.com/blog/?p=380

Thank you! I have already decided to go with something else based on your tip. The good news is that it will have greater capacity, will cost less, and be repurposed item. Awesome sauce.

The rocket heater can be shut off quickly? What if it is too good at heating the water and boils your fish?
There are YT videos of a soup kitchen/aquaculture setup that runs through winter purely via the heat from composting. On square footage the best shape for conservation of energy would be circular, giving maximum volume for least wall length.