The best course of action will be to narrow in on the type of land you want to deal in and then optimize your disposition strategy for that niche.It's a classic "Jack of all Trades, Master of None" issue.If you have a specific example in mind you want to share I'm sure we could provide some suggestions.

I just want to be able to provide a good life for my children. 

AND you cannot separately sell or refinance that ADU in the future.That said, I ran across this company that seems to specialize in this type of addition: maybe they could help? 

. - Contractors- Capital providers: JV partners, private money lenders (PMLs), hard money lenders (HMLs)sFor additional context, are you going to be flipping and actually selling or are you going to be fixing and holding for rental income? 

I recommend using the company that you have other policies with since they'll be able to provide you a bundle discount. 3 - Look at market rate, and charge slightly under.

I know that developers in the area have rezoned these kinds of plots and built apartment/office buildings and other commercial developments.I want to bring in an investor or developer to the deal who could provide the funds and knows the ins and outs of zoning.

any info you provide can help give some context 

This was renting for around $700 (garage for an additional $100). 

I have worked with a number of great CPAs over the years and would be more than happy to provide you with recommendations if you'd like?

I would add in addition to square footage and sleeping capacity look at similar amenities.If everyone in your area has a hot tub , then you need one too.