Hello Brad Buchanan,
Keep shaded .....Less evaporation.
Use a non metallic drum, no rust issues. Provide the bottom, or the lowest part of the vessel with a drain, just like you would do for an air compressor, for removing condensate.
Do not draw from the bottom of the vessel.
Filter the product before goes into the vehicle tank if you can. That is how I would do it! It all adds up to piece of mind.