Firstly, let me reintroduce wood-gasification (http://www.build-a-gasifier.com/fema-gasifier-plans/).  You tell me why it would be a bad idea to replace gasoline (non-renewable) with wood and other biomass (very renewable).  The FEMA supplied design was intended to be easy to set up and get going in the event of a catastrophic fuel shortage.  Sounds like a good place to start playing.  I saw Rocket City Rednecks hook a gasifier up to a gasoline generator and it ran just fine.  Yes it appears that tar build-up is a problem for wood-gas especially in the case of the FEMA basic design.  I wonder if the gas percolated through water would have less tar… how much additional energy would it take to make wood-gas a more long term solution.

After a little perusing it seems that the “DriZzleR Method” is pretty effective at cutting down the tar in the producer gas follow DriZzleR Method at http://thedrizzlergasifier.blogspot.com.au/2014/02/thank-you-pascal-to-give-me-opportunity.html

So how well will it burn human poop?  How does the poop need to be prepared?  Is it a reasonable use of resources to try and do such?  This could have solved the solid sewage problem of living off the grid.

I’ve heard rumors (http://news.mongabay.com/bioenergy/2007/05/researchers-to-develop-biomass-powered.html) of a thermoacoustic all-in-one heater/cooler being developed.  What is a reasonable amount of return for such a unit and how big would it be?  Energy input to temp change ratio?  Would self resonating cylinders be beneficial or hindering to establishing a standing wave?  How would it integrate and what could it integrate into?

Garbage: Can plastic be remolded and re-purposed with reasonable effort?  What about other trash like cardboard or metals?

Is it possible to use ground temperature in a mobile house situation to assist with heating/cooling? Would the naturally cool ground be an effective component for a sterling engine?

This is assuming that the tiny house is a trailer, how hard would it be to make it self propelled and what kind of spacial real-estate would that require?

Furniture and interior wise, how tight can utility be packed?  Multipurposed furniture/rooms.  Plumbing, ease of access, spacial arrangement.

Water treatment and collection.

HVAC.