I would like to start a pro forma for building a duplex to see if the asking price for that land would work for me or not.

Interested in knowing what your overall strategy is with real estate - does it form a big chunk of your total investment portfolio, does it get higher preference over stocks for appreciation, is it a growth strategy or preservation strategy, etc. 

Then you can form a plan.

Of course, with all things, the answers to all these matters will depend on the circumstances.California tends to have more laws on the books and requirements and restrictions that it can be a good idea to form a CA LLC for out of state property so that you as a CA resident are covered, and to try to have your contracts fall under the purview of CA courts.

Some questions to think on as you form a strategy:- do you have any money to use now to invest with- will you be a multi unit only, sfr only or mixed bag investor, or commercial- if you make an investment, or when you do rather, what number in monthly cash flow will you set as your floor in order to get involved in the deal (mine is 200$/month/property, or I don't buy)- can you find owner carry sellers- can you use a lease option or find lease option sellers- what grade of property or neighborhood/tenant will you be targeting- what fits best into your life as far as time management with the young kids at this point- do you have anything to bring to the table in order to partner up with someone to make all this a bit easier- according to your opportunities you find out there, what additional streams of income can you identify to go along with target properties or create as a result of being an investor (some people are agents, brokers, property managers, some use coin op laundry in multi units etc etc etc)All these types of things can go on forever as far as lists are concerned, but you'll have to find a comfortable place to start/enter investing and evaluate things as you go along and readjust as time passes.

It's a form a professional courtesy within a business relationship. 

I working on a pro forma, does anybody have any ideas for how best to go about it or rv parks in general.

Even better than income tax form a idealogical point of view (mine at least).Those own more property and use more public services by operating the properties should pay more.

An example of the new Act effecting people like contractors is that they can now ban together and form a large group and shop for coverage across state lines and thereby reducing the exposure of loss and getting lower premiums, especially if they had pre-existing conditions.We could form a RE Investor Association and apply for group coverage as well!

Sometimes there are a few kernels of wisdom though and usually form a big picture stand point make sense.