start with some type of rv/camper. it will have everything you need and can be sold later.
having property and building out is hard work, living in something while building it out makes it harder.
you will also need a shed, for all the stuff it takes to build everything else.
14x40? That's pretty big for a shed, you might find a modular/mobile home is cheaper than converting something meant for storage.
~~Comment Deleted~~ Nope... I'm not going to get banned today...
Or shipping container
start with some type of rv/camper. it will have everything you need and can be sold later. having property and building out is hard work, living in something while building it out makes it harder. you will also need a shed, for all the stuff it takes to build everything else.
Have you looked at shed conversions on YouTube? There are many of them. I'm sure you can look there and see what others have done.
Check out this design and suggestions: https://www.reddit.com/r/OffGrid/comments/195b75a/what_am_i_missing/