Devon,
It sounds as though you will be doing additional work to the structure. If so you may need to submit plans to the building dept. When you are having the plans drawn they can draw all the upgrades necessary for the foundation, Hvac and electrical. I build all over the country and have never found an inspector that is willing to design, they are only there to make sure you have built per code per print and what ever little wild hairs they have.
Keep in mind once you open this can of worms permits will need to be satisfied and the structure will need to be brought up to code and in the future sale of the property the unpermmited work will need to be disclosed.
A quick trip down to the building dept will yield a ton of info. Check on set backs, zoning ext, I have found while having dialog with the counter person usually one or two questions will arise that I had not thought of yet.
I don't know about Arizona but in Oregon if it is your primary residence you can do all the work on your house with out a license. You can ask the building dept that question when you are down there.
I don't think this is a dumb undertaking if the numbers work