The Start of my First "Micro-Micro" home: Planning

I have decided that this winter I am going to do the full planning of building a Microhome style small camper to learn some of the building techniques, and to gain experience before I try a "full scale"  microhome.  If this winter is super mild like it was last year,  I may even start construction.

Most of the Microhomes you see online are built on very large trailers and they have a high weight that requires a  F-350- F550 truck to pull them.   If you were to build your microhome on land as a cottage, this is not a concern to you, so you can completely ignore this restriction.   My ultimate goal is to build a permanent microhome on a plot of land as a "cottage"  but right now I dont own any land outside of the stamp sized plot here in the city that my house takes up more than 80% of.  So my first attempt is going to be a small camper that looks like a nice tiny cottage that my Jeep Grand Cherokee can pull.  It will NOT be spacious, as I am looking at using a 8' by 4' harbor freight trailer as the base.  But I have some plans for squeezing some extra room out of that platform.  And if I am able to find a better low cost platform, such as the Northern tool 5' by 8'  I may investigate that.  

I am looking at conserving space and making it light.  So walls will be 2"X2" lumber similar to RV construction but using foam board for higher insulation and lower weight.   Bathroom facilities in this design will be a portable toilet only.  Space is going to be extremely limited,  I am looking at a max of 43 Sq feet of living space with a tight sleeping loft that will have a useable 4' by 7' sleeping space but with sloping walls that peak at around 3'5" The largest space that needs to be "wasted" is the bathroom area at nearly 9 square feet.  Building very small for my first attempt forces me to be hyper sensitive to space concerns and space waste  Most people will sneeze at 9 sq feet, but I am losing almost 20% of living space over it.    I am not going to build in any water plumbing as it is a waste of space and resources for something so small.   I will be building in technology that will make the place feel like a home.  Networking, Wireless, and even a "whole house" automation system that will run off of the 12 volt power that it will be wired for.
Electrically, the whole place will be 12volt based. All lighting will be LED and 12 volt. I will wire in one 120V outlet in the "kitchen area" that will only be live when on shore power at a campground.  I am also going to install my solar power/charging system in this camper to test viability and real world performance.  I am going to aim for 200 watts of solar with about 600AH of battery storage.  Total normal daily draw should be less than 800 Watt hours considering that most of it will be wasted running the network and automation equipment 24 hours a day with the largest draw being the TV or the whole house audio for a few hours at a time.  Wall outlets in the loft and main floor will be standard Car power outlets to allow phone chargers, etc to be used. I am tossing around the idea of building in a 2 amp USB charge station to reduce clutter and the need for chargers.  I will use a marine fuse panel using standard car ATO fuses with a voltmeter, battery health meter, and master shutoff switch in the bathroom area.
I have not figured out heating, I will be using Polyisocyanurate foam board for insulation as it has the highest insulation value and has reflective film on the facing. two layers of this in the walls will give me a Wall R insulation value of 13.2 and a ceiling of nearly double that. Plus the reflective facings will decrease the amount of heat loss/ heat gain from outside. A portable small electric heater when on shore power will provide more heat than the place will ever need. I want the place to look like a cottage, so it will be sided with cedar (or pine) shake and all windows and the door will have to be custom made. I will probably use standard asphalt shingles to reduce noise in the loft while sleeping and it will actually add another 2-3 R value to roof insulation. main floor ceiling height will be at 6' 2" I need the rest of the vertical space in the loft. Entry will look grand as that will be open to the peak for access to the loft with a simple ladder that is stored on the wall by the door. Lastly to make it look even more "cottage like" I am going to embellish the entry end with a 1 foot wide "porch" with a matching roof overhang and a pair of Corner posts. This will be purely decoration but act as a step for the entrance and finish the look. This will overhang the end of the trailer by 1 foot I may put a short railing up as well to further add to the illusion. The entry door will swing outward to save space inside the camper, yes this is not ideal but every camper made has this design to save precious space.My biggest challenge is to keep the whole thing light. I need to come in under 1000 pounds so I have cargo capacity to put camping gear and bedding inside to use it as a camper. The trailer I am looking to use as a base is rated at 1700 pounds. So saving weight will be high priority. Luckily 2X2 lumber is less than a pound per linear foot. I still need to decide if I do a small table and 2 chairs for the main floor or build in a bench that slides out to add sleeping for a 3rd person.