For your situation as you want it, you would need batteries, a lot of them. PV panels are about 17% efficient at conversion. You can use solar to preheat water and use for heat as well.
A trailer has poor insulation so you need to figure out how to block it from the wind, and improve the window seals. To keep the hot out and the cold out as well.
If you have decent wind, and steady- a windmill or two would be of more use to you than you know. If you really are wanting to be off grid, and minimal impact- use a couple solar water panels and a wood fired water heater.
http://www.lindsaybks.com has a small publication on making one for a hot tub- this will work for domestic hot water too. Consider this instead of the electric point of use water heaters which use 5 to 30 Kilowatts in use. A propane fired unit would make more sense for you. Propane for cooking as well. One small burner of an electric stove is 220 volts- and 1000 to 1500 Watts The inverters for 220 are not cheap nor is the heavy wire that would be required. You can get idea of prices
http://www.northerntool pick either alternative energy or just inverters.
The reason for batteries is to able to store power generated by panels or wind turbines at periods of time you are not using electricity. Turbines will work all day as long as the wind is blowing above 15 MPH, you can get some useful info at
http://www.awea.org download their small wind guide. Northerntool also has wind turbines and solar panels.
If you were to attempt all solar panels, you would need in excess of 5KW for reliable power on the lower use side. Plus about 10 forklift batteries for the way you "want." Expect to pay in the range of 50,000 dollars for the system less installation costs.
With wind you can dump the excess power into heating elements in a water tank or into resistors indoors, or even into baseboard heat units if wired correctly- without the need for an inverter.
What really works against you is the aluminum wiring in the trailer. It is just not up to the current required at low voltages. 100 watts at 120 VAC for example is less than an ampere. 100 Watts at 12 volts is almost 9 Amps- the practical limit for the gauge of aluminum wire in use in most trailers.
So a practical setup with you changing to propane heat, cooking and hot water would be about 2 to 3 kilowatts of generation, either from panels or turbines or combination of both. One forklift battery might be enough, two would be better. This could be done for less than 30,000 dollars.
It might make a good deal of sense for you to spend a lot of time on this site:
http://www.builditsolar.comThe best solution is to also put up a well insulated structure to live in addition to the power generation. Building codes are amenable to alternative building methods such as straw bale, rammed earth, cordwood, and other nonconventional materials and methods. You might need to locate the online information and references to get some approvals as a homestead- a requirement if any loans or insurance is involved.
